23

Chapter 23: Gym Time – Part IVSummary:

Quirk Analysis of:

Itsuka Kendo - [Big Fist]

Ibara Shiozaki - [Vines]

Yui Kodai - [Size]

Sen Kaibara - [Gyrate]

Hanta Sero - [Tape]

Notes:

(See the end of the chapter for notes.)

Chapter Text

"Gooood morning beautiful people!" Jumping over the last step of the stairs, Mina addressed the group already mid-way through their breakfasts.

"Good morning, Ashido," Yaomomo greeted in return, followed by a couple of happier replies and a few grunts. Not everybody could be a morning person. 

"Please, keep it down," Kaibara groaned. "It's too early to be shouting around." 

"I'd also ask you to refrain from raising such thunderous greetings," Shishida said politely. "I fear I might risk activating my Quirk because of the sudden scare." 

"Uh, sorry," she teethed, getting her own bowl. 

"It is nice to see someone else being energetic in the morning," Kendo welcomed her to sit closer. 

"Eh, I try." She giggled and looked at the girl's choice of wear before continuing. "Already in a gym uniform?" 

The redhead nodded with a proud smile. "Yeah, I went out for a run with Midoriya to work an appetite. He's yet to come back though." 

"I believe Shoda and Shinso to have joined him too in the last quarter," Shiozaki offered. 

"He's been out for, like, an hour," Toru commented, shrugging. 

"Does he ever stop?" Kaibara asked. 

"I have my doubts," Yaomomo answered with a quiet but audible hum. 

"Remind me, how did I accept to train with him?" the black-haired teen asked.

"Because, contrary to more than half of our class, he actually knows what he's doing," Kendo said with a sigh. 

"And he's already helped us improve by a lot!" Toru added, her spoon clinking to catch more attention. 

"We shall see to make the best of this chance then," Shishida affirmed. 

Shiozaki raised her head, turning to the 1-A girls. "Do you think there will be more people joining us?" 

"Hard to say," Yaomomo thought for a moment, "but I doubt he'd leave anyone out." 

And wasn't that the truth.

His morning exercise had attracted some onlookers and some fellow runners, like he'd hoped. Itsuka was almost always a given, while Hitoshi and Nirengeki had a lot to catch up on. He wondered how long it would take to get more than ten up and running by dawn. Or twenty. 

A nice shower had refreshed him, and he'd gotten his fill faster thanks to something they'd left for him. 

From that point on, Izuku started his favorite past time: being there. 

Six more hours went by like a breeze, and before they knew it, they were stepping inside Gym Beta with Snipe going to stand over the wall.

Izuku looked at his thirteen fellow students, some visibly more excited than others but, overall, a nice group. He could deal with sets of under twenty without resorting to splitting himself in two. 

"Well then, it's been a while since last time, but I usually like to start with those of you I haven't analyzed yet. Which today means almost everybody here, so who would like to start?" 

"I believe we should let the ladies go first," Jurota stated, being met with a chorus of "Okay," and "Fine by me." 

Izuku moved his eyes on Itsuka, Yui and Ibara, each waiting for one of the others to step forward. After a couple of second, the redhead stepped forward, taking the lead. 

"There's no need to chicken out, guys. I'll show you how it's done," she jokingly teased. 

"Thank you for your trust," Izuku rolled his eyes, but kept a smirk on. "So, Kendo, your Quirk, [Big Fist], seems like a pretty straightforward gigantification, but there are a couple things I'd like to check." He turned to the side, walking towards a platform that could have probably supported an entire truck. "Step on that please and grow your hands as much as you can." 

She didn't complain, activating her Quirk as he had asked for. Standing in front of the screen connected to the scale, Izuku opened the weight graph to show what was changing. Momo's little version they had used for Mezo really wouldn't cut it for this, and this one had some nice tricks to it. 

"Here," he moved his finger, pointing to a couple of different spots, "this shows how your weight shifts before and after your Quirk's activation."

"Uh, I'm getting quite heavier," she looked at the numbers showing how her enlarged hands had added around six times her own weight. 

"And you aren't affected by it, right?" 

"Nope," she waved her gigantic left normally, "feels just like usual. I feel how it's bigger, but it doesn't feel much harder to move." 

"And how about moving in water?" 

She looked thoughtful for a moment. "No, that's harder. Isn't it normal?" 

"Yeah, and that's a relief. It means you don't have a passive way to disregard air resistance and similar things. That would have made thing more complicated," he sighed, thinking for a moment of Ochaco's destructive properties. "Anyway, let me change a couple settings..." he started tapping on the console. 

"How does he know how to use that?" Sen asked to the group. 

"He's full of surprises!" Mina said, not answering at all. 

"I've spent a few afternoons walking around the campus," Izuku replied as he worked. 

"But wouldn't you need a teacher's permission to use training grounds?" Ibara asked, slightly frowning at the prospect of rule breaking.

"It's fine, the principal knows. I've got his blessing," he added, making his friends give him looks shock and surprise. Snipe choked on air before covering the act with a few fake coughs. 

- Nezu must not have told them anything more than strictly necessary... those poor teachers... - 

"Anyway, Kendo, I can see a couple of interesting things about your Quirk's function here." 

"Oh? Do tell." 

"Your body is able to disregard the added weight of your hands, so as not to put a terrible strain on your muscles and bones. What's interesting though is this." He pointed to a precise point on the screen, were the colors related to the weight placement went into darker tones. "The platform is calculating your weight and its distribution, and it's sensing a lot of pressure distributed equally in the space around your feet. And I mean around, not under. Instead of having four hundred kilograms where your feet are placed, the load seems to be smoothly dispersed inside a circle... Could you stretch your arms and see how much further your fingers can reach?" 

As she complied, the graph didn't change, and the distances appeared to be mostly identical. 

"It seems like your Quirk is managing an automatic distribution of weight in a circular area, delimited by your arm's length," he declared. 

"Which means?" Sen asked, not seeing the point. 

"Which means that, if I'm right, she might just be one of the best weight-carriers in our year," he smiled. "If it helps you visualize it, it's like she's always wearing a pair of snowshoes. Or when her Quirk's on, at least. You know, those things that help distribute your load around, so you don't sink into deep snow?" 

Sen and a couple others, mostly from hotter of sea-side regions, shook their heads. Others, like Momo and Yui, who had surely seen their fair share of skiing and snow resorts, nodded, even showing an example. 

"The thing is, she doesn't get the extra impediment, but she does get all the benefits. The weight of her hands should be crushing her shoulders, but it's simply not. Plus, her whole body gets benefits from this, so her equilibrium should be near infallible." 

"Never fell once in my life," Itsuka smiled proudly, making a big thumbs-up gesture. 

"A bit exaggerated, but you get my point," he chuckled. "Want to try to see if it works with things you're carrying?" 

Hastily raiding the gym's storage in search of weights and other carriable objects, they soon discovered how, in fact, anything that touched Itsuka's body fell into the category of "carried object," be it an item or a person. 

"How did we not discover this during the cavalry battle?" she asked at one point, more and more stupefied. 

"When do you think I got the idea to try this stuff?" he replied, making her sigh with an "Of course."

- Yeah, of course I thought about it during the cavalry battle, obviously. Best alibi. - 

"The Quirk seems to be able to differentiate between your body and others," Momo helped in their analysis. "While your body is perfectly balanced, I can see that the dumbbells' weight isn't as spread out as yours is. I'd say there should be a forty to fifty percent reduction." 

"Which is still great," Izuku hummed, before adding, "Imagine how many people you could carry out of danger at once." 

"Damn, super helpful," Mina whistled. 

"A great boon indeed," Jurota agreed eagerly. 

"I think we've got one last thing to try," he said, stepping closer to get a few steps away from the edge of Kendo's range, gesturing to her to repeat the arm-stretching. "You can grow those to their max in half a second, right?" 

"Zero point forty-eight. I'm improving, but every time I get to increase my size further it takes that tiny bit more, so..." 

"No worries, it's still improvement. Now, when you make your hands return to normal, do you visualize them as shrinking back to your wrist?" 

Itsuka raised an eyebrow, thinking harder about the act that was already second nature to her. "Yeah? I'm getting them back to how they usually are, so back to the wrist, yeah." 

Izuku hummed, looking thoughtful. "Have you ever tried shrinking them in the opposite direction? Try this: Instead of making it go back to your wrist, imagine the movement going from your body to the tip of your fingers." 

The students of class 1-B looked between each other, confused, looking for any kind of sign of an explanation from their rival class. They found nothing but looks of "oh, he's doing it again." 

The redhead nodded warily but concentrated to follow his instructions. The transformation being practically immediate was typical, but the way Itsuka got launched forward with a yelp of surprise definitely wasn't. 

Knowing what would happen, Izuku managed to jump and grab her before she planted her face into the ground, placing her upright again as she remained still like a piece of wood.

"And that's another win for me, Miss 'Never fell once in my life,'" he smiled kindly as he let her go. 

"Wha- What was that?" she sputtered, still shaken by the experience. 

"Yeah! What the hell was that!" Sen joined into the question, ignoring Jurota's and Ibara's request to "moderate his language."

"Another interesting interaction between your speed of growth, your hands' weight, and momentum," he explained. "You're used to bring it backwards, which prevents a change in momentum. But by moving your entire body forward you're converting the speed of the transformation and the change in mass into a burst of movement, a lot of force." 

"It looked like a rubber band to me," Toru thought aloud. 

"Mm, not that bad of a comparison," he snapped his fingers. 

- I'm surely taking that for next time. - 

"Guys, that was a dash..." Mina looked the most amazed of all. "I so gotta tell Kiri." 

Most of their videogame-lovers were absent, but they'd surely go crazy seeing something like that.

Izuku turned to the stunned representative with a supportive smile. "Getting a good hold on it would open a lot of possibilities for you. Engaging, dodging, jumping... I think your style would benefit immensely from it." 

Itsuka clicked her tongue, gathering her thoughts. "Yeah... Imagine closing in instantly... Nobody without superhuman speed could dodge..." A grin formed under her fingers. "Oh, this is great..."

"Oh lord," Ibara joined her hands in prayer. 

Jurota cleared his throat before reassuring the others. "I believe she might be praying for Sir Monoma's health." 

Only moderately reassured, the group went back to imagine possible applications. 

"The result is surprising... Should we try and see which speed you can reach?" Momo's eyes glinted as she created a chronometer, already taken by the eagerness of the experimentation. 

After discovering that she was able to dash at nearly forty kilometers per hour, a speed comparable to a pre-Quirk Olympic 100-meters runner, Izuku decided to give her a breather and move on to the next girl. 

Yui simply gave Ibara a nudge, making the holy woman of 1-B take the stage. 

Izuku decided to go with a humbler approach. "Shiozaki! I forgot to congratulate you on your fights of the other day. The way you used your vines to protect Hagakure and trap Asui was superb." 

"Yeah!" the invisible girl happily joined in the compliment. 

"I completely fell for her moves," Hanta confessed with a sigh. 

Ibara lightly bowed her head, the hint of a smile showing that she'd appreciated the comment. "Thank you, but I will confess I had hoped for something more, despite how prideful that must sound." 

"There's no fault in wanting to do your best and believing in yourself," he shook his head. "And being in the top eight of a hundred and sixty students is an achievement, Shiozaki. You should be proud." 

"Indeed, your brilliant performance brought great honor to us all, Miss Shiozaki," Jurota declared. "I'm sure all of our classmates would agree." 

"At least someone made it there," Sen rolled his eyes, receiving a huff from Itsuka and an annoyed hum from Yui. 

Having finished the small introduction to ease her into the training, Izuku began. 

"So, Shiozaki, I've seen your Quirk a lot, and I think it may be one of the best I've seen this year in regard to sheer power. Plant-related Quirks aren't that rare, but those that allow that much of an area of control are. The only case I've seen recently is Kamui Woods, and he's sure to rise in the rankings to be in the first twenty this year." 

- Top ten would be more accurate, but I'd have to explain that. - 

"Thank you. [Vines] has been a gift that I've never stopped being thankful for," the girl raised her joined hands with a solemn smile. 

"Well, it surely is a boon," the boy admitted. He had once been in awe at how much territory the Hero Vine could cover by herself in her prime. It was admittedly a bit scary. "For starters, I would like to analyze the vines themselves. Let's see..." 

Taking a strand of the plant in his hands, he made a show of thinking aloud, mumbling a bit as he went through what he remembered. 

"They're quite heavy... the greenish color is typical of some types of vines, but the thorns aren't usually found in those same plants. It reminds me of lianas by the way they move and entangle, but they're much more like roses in general... despite the thorns not resembling those at all." 

"Why, are there that many types of thorns?" Toru asked, always interested in flowery subjects. 

"A lot. Plants need their own defense systems," he chuckled, pricking his finger slightly. "But these are too far apart to be a rose's prickles. If I remember correctly... there's an ornamental plant from South America called Bougainvillea which show thorns a lot more similar to these." 

"I didn't expect you to hold that much knowledge on flowers, Izuku," Momo said, puzzled by another show of education not usually found in school. 

He rubbed the back of his head sheepishly. "My mom really likes flowers..." 

"Aww, adorable," Mina snickered. 

"A-Anyway," he turned back to his search, faking some shyness just for fun. "Can you feel it when I touch them?" 

"Yes, but the sensation grows duller the further away it is from me," Ibara admitted, stretching a strand for a dozen meters. "Up to this point I can feel touch as if it was on my skin. After that it starts to become muddled until it vanishes completely." 

"A good range. I think that it may grow with time and practice," Izuku contemplated, looking very interested by the fact. 

- Now, a step further, carefully. - 

Izuku slowly made his way up the strand, ending up "by mistake" in front of the girl. His face showed some nice shades of red only to her, as his back was turned to the others. Ibara usually appreciated being with someone that seemed as socially awkward as she was. 

"Could I look at your, uh, hair now?" he met her eyes, hoping that she'd find the sincere respect in his own acceptable enough to allow him to get closer. 

It may have seemed fitting that the girl with rosy thorns in her hair would be hard to approach, but Izuku knew how difficult it was for her to open up to others, be it physically or socially. 

She nodded, getting closer an letting him inspect the green substitutes sprouting from her scalp. Thanking her, he started to raise and study the tangled ensemble in a very meticulous fashion. 

"I see, it's certainly a mutation Quirk. The ones closer to your head seem much more like typical hair, they're smoother... and I can't see thorns here." 

"Yes, those tend to grow only under my neck," she replied, clearing her voice a bit. "I believe it might be a way not to scar myself." 

"Yeah. You can't control the thorns on your own?" he placed two fingers around one of the many spikes. 

"No, I have no real control on their surface state, only on how the entire ensemble should move." 

"Got it. But you do control their thickness, do you?" 

Ibara nodded again. "Only up to a certain point, but yes. They can't become as thin a hair, but their diameter can go from a few millimeters to a few centimeters." 

"Amazing, that should make it much easier to get into the next step..." 

Izuku steeled himself, preparing to play the bad cop for a bit. 

He heard and ignored a slight sigh from the vestiges. 

- It will hurt me more than it'll hurt her. - 

"Not an improvement, Sprout," Nana chided with a tone too soft to be taken badly. 

"I'll be blunt. Shiozaki, from what I've seen there would be little to no point to train your Quirk's strength. It's powerful enough to break through Cementoss' concrete, and that should suffice for now." 

She looked a bit taken aback by his words. He knew that she had mostly received advice about increasing her power, something that only changed later on, when Vlad King had gathered that she needed to change her focus. 

"Tell me: when you caught Tsu and Momo, and when you hit Tokoyami, did you mean to keep them trapped or to hurt them?" 

A pained expression of shock rose to Ibara's face. "I- I meant only to hold them! I swear." 

"Easy, I'm not trying to blame you for it," he raised his hands to soothe her. "It was a fight, so some injuries are par for the course. But I've personally seen the marks your thorns left, and those weren't pretty." 

She looked even more dejected, but he quickly added more words to get to the point quickly. 

"I don't mean to offend, trust me, but what you're sorely lacking in is fine tuning. But the good news is that it's an easily solvable problem!" 

Izuku turned towards his bag, taking out a few items he'd prepared for the occasion: sets of wooden chopsticks and small objects of various shapes. 

"I want you to try and use your vines to hold these," he pointed to the sticks, "and use them to move around various things. We'll start with the bigger ones, then slowly make our way to the smaller and rounder ones, which should be harder to keep steady." 

"How is holding a pair of chopsticks going to make her control better?" Sen asked, his tone having lost most of the aversion after seeing what Kendo had gained. 

"We aren't stopping here. This is only the first step." He took out more sets of utensils, placing them down, reaching an even dozen, as he explained. "How long did it take you all to manage to eat with chopsticks when you were children?" He asked. 

The group answered, most of the answers fluctuating between four and five years old.

"Most Japanese children learn about that age. Before that few have the control necessary to make it a habit, and even then, it would take a bit. Next, do you think you'd be able to hold a glass marble with those?" 

"Mm," Yui nodded, followed by affirmatives from Momo, Itsuka, and Jurota. 

"No way, too slippery," Mina tsked, followed by a "Nah" from Hitoshi and more shaking heads. 

"Well, I want you to imagine that carrying a marble with chopsticks should be your comparison for carrying civilians with your Quirks." 

At that, a deadly silence fell on the room. 

"Shiozaki's vines, Kendo's hands, but even my Quirk, Sato's, Shishida's, and everybody else's. We are all powerful in our own right, but the slightest mistake could break someone's spine and make it so that a rescue turns out to be a disaster. That's not something we can ever allow to happen." 

He eyed them all seriously, turning back to Ibara who now looked like too many things had been put on her mind at once. 

"What I'm trying to do is teach you how to carry something incredibly precious with the outmost care. Now it's a ball, an egg, or a marble, but one day you may have to carry a person's life in those vines. And I'd like to think that you'll do your very best to make sure that no harm would ever befall someone you're guarding." 

Something changed in her eyes as her determination grew, her nodding solemn as she crossed her fingers again. "Yes, I shall not err. I will do my best to be worthy of Heaven's grace." 

Izuku smiled at her widely, showing a refreshing trust after the talk he'd given. "I'm sure you will! You can take those and learn at your own pace. Try to get comfortable with one set before moving to the next. You may try to see if you can let go of the objects and catch them before they hit the ground, it should improve your reaction time as well. I'm sure you'll be great at it." 

"Thank you. Then I'll be sure to prove you right," she smiled back, going back to the group as her vines caught the instruments that she'd spend most of her time mastering. 

"Kodai, you're up," he called the next in line. 

Yui stepped forward while keeping both of her hands behind her back, her eyes focused on Izuku with that intensity that was part of her signature. The rest of her expression was still as indecipherable as ever. 

Most people would never be able to get a read on what Yui was feeling or thinking. They relied on what appeared on the surface to deduce what was held beneath, but too many morons would just see a smile and relate it to happiness, or a frown and relate it to anger. They sorely missed the nuances of the infinite array of emotions a person could feel, the subtle differences between sorrow, regret, misery and despair, or between cheerfulness, joy, pleasure and satisfaction. 

What happened then when someone like that, who couldn't read an expression for his life's sake, met someone like Yui? Usually, they started by adorning her with a series of labels. 

Some easy to give out, forgivable for their simple-mindedness. 

Mature. Quiet. Calm. 

Other less so, brought by further failed attempts to understand her. 

Indifferent. Cold. Introverted. 

Finally, the little golden stars on the pile of prejudice. 

Asocial. Emotionless. Un-affective. 

Izuku knew that she'd been hurt by words before. Yui never showed it, as she kept up a front that was like a placid sea, hiding horrors in the deep. But when she'd broken down... 

Izuku had no intention of allowing anything like that ever again. 

What most of those judgmental morons would never get to see was how much Yui actually showed of herself. Most of it was subtle, the small movements of her fingers, the way she turned her neck to one side, the slight positioning of her feet. But most of all, her heart could be seen in her eyes, if one knew when and how to look. There, she was more expressive than Mina was loud. 

"Okay, let me see if I have it right on your Quirk. Oh, you don't have to answer vocally if you don't want to. I'll try to make my questions yes or no." 

Izuku had once found it strange that despite her apparent near-mutism Yui hadn't learned JSL, but she had no qualms about speaking up when needed. It was just her concept of "needed" that was a bit rough around the edges. 

The hint of surprise on her face lasted for less than a second, covered by a nod. He started by listing off anything he could have reasonably seen during the festival. 

"Your Quirk affects the size of object you touch with at least five fingers at once-" 

"Oh, just like Uraraka's," Mina interjected. 

"Oh yeah, she's also a five-point activation with her gravity," Itsuka recalled, the memory of their aerial battle still quite vivid in her mind. 

"I wonder if the resemblances stop there," Momo wondered. 

They didn't, and beyond Quirks as well. But that was too much information for everybody else here. 

"Ahem," he brought them back to attention. "Yes, it's a five-point fingers activation requirement and, just like our classmate, you need to connect your fingers again to release the effect. You can both increase and decrease the size of what you're touching, although we'd have to see by exactly how much. I'd say from a few centimeters to a few meters, and everything in between. The Quirk doesn't change the form of the object during the change, and it doesn't prevent alterations from outside sources." Yui nodded along with his every inference. "Lastly, I don't believe I've seen you use it on any contestant, so there is also a living-beings excluded rule." 

Momo seemed interested to have found someone else with a similar limit, but they'd have time to discuss about that later on. 

 "All correct," Yui stated. 

"Great. Then, let's get to the more interesting stuff. We know you have a size limit, but do you know precisely what that is?" The girl shook her head, prompting his next phrase. "Well then, let's find it. Please, release any change you're keeping with your Quirk, if you have some. We need a clear slate to get realistic results." 

Yui nodded, pressing her fingers together for a moment before stepping forward with him. 

Working with a very big and precise scale helped a lot with this kind of inquiry, and Izuku was once again relieved of having the principal's support. Placing a one-kilogram, perfectly-square weight before Yui and asking her to increase its size to her current maximum, he observed her operating her Quirk. 

"Do you have a limit for how long you can hold it that way?" he asked, smiling as she shook her head. "No time limits, that must be nice. Okay, if it won't give you any discomfort, we can check a couple things..." 

Izuku took out a notebook and began taking the measurements as he talked. "The cube should be 100% iron, with a density of 7.87 g/cm3. Its starting mass was of 1 kilogram, or 1,000 grams, and its side was 5.03 centimeters. Now, its mass has increased to 524 kilograms, or 524,000 grams, and its side is 40.5 centimeters." 

"It doesn't look that much bigger," Hanta said, bewildered by the smaller-than-expected change. "Didn't you say she could increase stuff by meters?" 

"She can," Nirengeki looked confused as well.

"Are you sure that's your limit, Yui?" Itsuka asked her friend. She had seen increase things to be much bigger than that cube, so something didn't sit quite right with her. 

Yui simply nodded again. "It won't increase further," she replied curtly. 

Izuku smiled. "I think I've got a hunch as to the reason why. Kodai, do you know your precise weight?" 

The girl shook her head and, understanding the inquiry, stepped onto the scale. The count increased by 52.3 kilograms. 

"52.3, or one tenth of 523. Do you know what that number means?" he asked, appreciating the not-so-lost glances coming from their 1-B companions. Nirengeki and Jurota didn't slouch on studying, ever. 

"It's the mass," the Vice Representative mumbled, "it's her mass." 

"Yeah, ten times her mass to be exact, and that's why the increase is limited." Izuku turned towards the silent beauty as she gazed at him, listening intently. "Your power isn't related to size, or at least not directly. [Size] likely takes your own weight as its upper limit of how much it can transfer into other objects. Kodai, you can release the block," he moved to take the object and replace it with a wooden replica. "Try hitting your limit with this one. It's bigger, but it's only one kilogram again." 

This time, her touch increased the side of the cube by more than a meter, making it a lot bigger than their first attempt. "See? It depends on the density of the material. The mass she can give stays the same, so of course something that's less dense should become bigger. And remember that these are cubes, not empty objects. Something that's only a wrapping or a container should easily become much, much bigger." 

"Ah, that would explain why we've seen Miss Kodai enlarge things to a much larger degree before," Jurota agreed with a resettling of his glasses. 

"It's nice to receive such a detailed observation," Ibara thought aloud, half of her mind trying to keep up with her exercises. 

"Does that mean that the more she weights, the more she could do?" Rikido questioned. 

"It does seem like the most sensible deduction," Momo nodded. 

"Oh, then you should build more muscles! They weight more!" Toru proposed, trying to add a fellow girl in need of improving her strength to her own regimen. 

"They're denser, yeah. It wouldn't hurt anyway," Itsuka concurred, knowing that many of her classmates had slacked off a bit regarding their physical fitness. 

"Is that all?" 

Izuku turned to Yui. Beneath the immutable zest, he could see the curiosity he'd piqued, the hunger he'd started to feed. Under the surface, Yui was a girl like any other. And, just like most of the other girls in the Hero Course, had a desire to improve herself that rose to the stars. 

She had loved what she'd learned, and she wanted more.

"No," he smirked a bit, handing her the iron cube. "Could you shrink that one to your limit?"

She complied, reducing the object until it was nothing more than a nail-sized die between her fingers.

"And now, try increasing that one again," he pointed to the wooden block with his thumb, basking in the sudden spark of understanding that burst in the girl's eyes. 

Yui didn't waste a second, turning around to test the theory while barely containing her excitement.

More mouths fell open in surprise as the material grew anew, even if only slightly.

"Want to add more?" He offered her more items, which she promptly reduced to miniature replicas before letting the stolen mass flow into her main work. With a few more centimeters added to the wooden cube, Izuku answered the group's questions. 

"Your Quirk doesn't only use your own mass, but everything you take by shrinking objects is added to your upper limit. For some reason it doesn't seem like it's also multiplied by then, but I hardly think that's going to be a problem." 

"I don't have a time limit," Yui's voice wasn't loud, but carried all of her amazement. "I could virtually increase it with no upper limit." 

"Precisely," he grinned. "And if you could learn to only release certain objects from you power, leaving a good storage of mass to give and take at your own leisure, then you wouldn't have to worry about any limit at all." 

"Damn, endless growth and shrinking..." Sen mumbled, knowing that her one obvious weakness had just poofed away as if it had never been there. 

"That's amazing Yui!" Itsuka cheered her friend, joined by the others. 

"Controlling the mass you'll be moving around will be crucial to your technique, so I'd suggest getting some support items to make most of the calculations for you. And to learn how to only release a part of your power... I'd suggest starting with just two items and concentrating on releasing either without the other being influenced by the act. It'll get easier once you've got the basics down." 

Yui kept her eyes trained on him for a few seconds. Gratitude wasn't that rare of an emotion for him to see from others, but the respect he saw there warmed him inside. 

"Thank you," Yui said, the corners of her mouth moving up ever so slightly. She had her back turned away from the others, so they'd have to wait to see it again. 

"You're welcome. So, who wants to go next?"

The boys looked between each other for a few moments.

"I'm fine going last," Jurota conceded, doing the gentlemanly thing.

"You can go first, Kaibara," Nirengeki offered, letting the dark-haired boy step forward.

"Thanks," Sen said, stretching his shoulders a bit as he moved his gaze on Izuku. "You haven't seen my Quirk much during the festival, right?"

- Didn't have to. -

"I've seen enough," he countered, "you can rotate parts of your body at high speed, right?"

"... Right." Sen mumbled with an expression that told him he had wanted to explain it himself.

"I know how to keep my eyes on what's going on around me, Kaibara. And let's say Monoma and Bakugo didn't make it hard to spot you all," he chuckled. "Anyways, does it work only on your limbs or on everything else too?"

"My whole body, yeah." The teen started showing how his Quirk operated, from the tips of his fingers, to his shoulder, and to his legs.

"You're still keeping your midsection still," he pointed out. 

Sen frowned a bit. "It's damn uncomfortable to rotate that. I either get a headache or a stomachache."

He matched the frown. "So you're fine with not improving because you're getting light-headed or nauseated?"

The other teen held his expression for a few seconds before giving up with a sigh. "'right. Gimme a sec."

Withstanding the bad feelings, Sen started to rotate from his stomach down, his lower parts becoming a blur. Izuku started examining the boy on all sides by circling him. 

"Is there a limit to how many parts you can rotate?" 

"Nah," Sen started showing his left hand as it blurred, quickly followed by the right arm. "I could make everything move at once. It's just strange not to have something... 'solid' somewhere." 

"Strange, but not wrong," Izuku rehashed. 

"No, not wrong. Why, does it matter?" 

Izuku nodded. "Many Quirks usually give the user a feeling of deep wrongness when they start doing something they shouldn't or that's going to be detrimental to them. Prime example, I get that feeling when my muscles start hurting because I'm using more strength than what I can handle. If I keep at it, my bones break, so that's a pretty good alarm bell. If your Quirk isn't telling you to stop, it means you can keep at it." 

Sen answered with a curt nod. "Anything else?" 

Izuku swiftly moved a hand to catch Sen's arm, stopping its movement abruptly. "Mm, weird. I felt a lot of collision while I was catching it, but now that it's still it's back in its original position. At least that means that you won't end up with twisted body parts if you're interrupted mid-spin." 

"You could've just asked," Sen huffed. 

"Sorry, I prefer a hands-on approach," Izuku smirked letting go. "You haven't stopped spinning everything else, so that's another point in your favor. I think your body keeps its basic form despite the rotation, as if the parts you're moving weren't really part of the whole anymore..." 

"Why do you say that?" 

Izuku pointed downwards. "Because, if that weren't the case, rotating from your stomach should move everything. Up or down shouldn't make a difference. You're clearly using your y axis as the center of your spinning, so your whole body should rotate around that." 

"That makes sense," Nirengeki followed, drawing lines in the air with some gestures, "if you think about it like a spinning top, there is no way the top could be still while the bottom is rotating." 

"I know a thing or two about that," Mina rolled her eyes. 

"Exactly. The fact that you aren't just completely losing yourself to the rotation means that your Quirk has a separating effect on your body parts. And that' where the fun begins." Izuku told Sen to follow him to another station, taking out a laser pointer and sticking one tiny black dot to the arm he'd stopped, one over his wrist, and one to his index finger. "These should tell us how fast you're going. You can you start again at your maximum speed."

Sen complied, the whole limb blurring into small a colored tornado. 

"It's counting three rotations per second. Now, Kaibara, can you also start rotating your wrist?" 

Sen looked became questioning. "You mean stopping my arm and using my wrist?" 

"No," Izuku replied, serious. "Keep your arm going and add a rotation to your wrist on top of that." 

Kaibara's eyes widened a bit. "I've never tried that before." 

"I figured, but that's no reason not to, is it?" 

"Fine," Sen stated, starting to stack his Quirk's effects for the first time. A moment later, the air movement around them intensified further, as everything from the wrist up began moving increasingly faster. 

Izuku counted. "And that's nine rotations per second. Add your finger to that, if you can... and that's twenty-seven. Can you keep it up?" 

"Yeah, I think I can. It's harder, but I can," Sen replied with his frown growing like his concentration. He began moving his arm around, finding the whole process strangely difficult. 

Any further doubts were obliterated when Izuku offered him a wooden plank to punch through, which he practically reduced to dust. 

After a few more minutes the power relented, Sen's arm falling on his side as he almost collapsed on himself. Izuku rushed to hold him up. 

"That was... tiring," the teen managed to get out with ragged breath. 

"Sorry. Does your Quirk consume calories to work?" 

"I wouldn't know, but now I think it does. My stomach feels empty as hell." 

"I've got some energy bars. Mina, could you?" The pinkette happily jumped to the rescue, bringing the goods as he kept Sen on his feet. 

"I've never seen your Quirk leave you so tired, Sir Kaibara," Jurota stated, confused. 

"You never had problems with stamina," Itsuka recalled, "besides the long-distance run, at least." 

"Yeah, I didn't, but I guess this is a lot harder." 

"And a lot stronger," Izuku offered. "You're practically multiplying your rotation speed each time, so your fingers moved nine times faster than your arm. That consumed a lot of energy, but it could also pack a much stronger punch." 

"For sure," Mina added, "if it's like my spinning throw, it's much better than what you're doing normally." 

"It's not exactly the same, but the basic principle should work for this comparison," Momo nodded. 

Izuku agreed, starting to add to the explanation. "You're still going to need support items to cause damage without hurting yourself, but that's just the start. Separating by arm, wrist, and fingers was for seeing some clear-cut differences, but I think you should be able to do it with any point of your body, even if it's just slightly apart. And you could also raise both your rotation speed and your number of stacks..." 

"So being nine times stronger is just the start." Sen looked at his fingers, flexing his arm while wearing a new smirk. "I like that. Thanks, Midoriya, you're not so bad after all." 

"Thank him properly," Itsuka huffed at the boy before Izuku could interject. 

"It's fine. He's not that bad too," he joked, exchanging a glance with Sen that settled some mutual respect. He was rough around the edges, but he could be focused and calm when it counted. He'd need him to help keeping Monoma in check for a bit. 

"We should let one of you guys have a turn," Nirengeki turned towards the two boys from 1-A. 

"Ah, I'm fine waiting," Rikido shrugged. "Sero?" 

"Alright," the black-haired teen smiled widely and cracked his knuckles, preparing to get his own power-up. "I don't think I'll have to explain my Quirk to you, right Midoriya?" 

Izuku shook his head with a grin. "I think I've seen enough in the past month, thanks. You'll still get to answer some questions though." 

"Lay them on me!" 

Izuku appreciated the easy-going nature of Hanta. Despite not being overly powerful, he had always showed great control of his surroundings, light feet, dexterous hands, and a good head. Sero could also be serious when he wanted to, and he was always ready to lend a hand in moments of need. If there was one thing that Hanta was, Izuku could summarize it in the word "dependable."

"Nice to see you so eager," he rejoiced, starting to speak. "Have you ever had your tape chemically analyzed?" 

"Mm, nah, never felt the need to. It's just tape, you know?" 

"I would recommend you stop undervaluing any kind of information you could get on your Quirk. Luckily, I did it for you." Izuku took a folded paper out of his bag, under the confused eyes of the group. 

"How d-?" Rikido started, being immediately interjected. 

"Sero leaves a lot of this stuff around after each training session. The hardest part of getting some to send to the chemistry lab was not getting my hands stuck on it." 

That had been a pain and a half. 

"Fair enough," Hanta shrugged, not really caring about anything more than the results. "So?" 

"Just like regular tape, the adhesive side is methyl acrylate, or (C4H6O2)n, while the coating is polyethylene, or (C2H4)n. Standard components." 

"Nothing special about them, uh?" Hanta seemed to be just a bit disappointed. 

"On the contrary, any chemical is worth something if you learn how to use it," Izuku began raising his mood. "How much do you know about chemistry?" 

"Uh, I'm a bit behind on the subject..." the black-haired teen put on a guilty smile. 

"No worries," Izuku reassured him. "Methyl acrylate is, of course, sticky. It's not incredibly high on the scale of adhesive materials, but the quantity you can produce makes up for that adequately. What's more, it is flammable at 2 degrees Celsius below zero, and its vapor can irritate the eyes and the respiratory system quickly. It's also highly toxic by inhalation, ingestion, and skin absorption, just so you know." 

"Who the hell would eat tape?" Mina asked, trying to picture the act. 

"Someone trying to get out of his bindings?" Nirengeki hypothesized, not getting the rhetorical question. 

"It would make for a good deterrent then," Momo claimed. 

"Yeah, it would be. Any Villain with the ability to burn through the tape would need to pay attention to the fumes, which isn't that easy during battle or in enclosed spaces. I'd suggest you add a respirator to your mask, just in case." 

"Works for me," Hanta agreed, mentally taking notes. His costume already provided him with a helmet, but he hadn't thought that much about that kind of breathing problems. 

"Moving on, the polyethylene, or PE, is interesting too. It's the most produced kind of plastic, and it's usually made from a mixture of similar polymers of ethylene, with various values of n. It's usually divided into two kinds: low-density and high-density." 

"What's the difference?" the other asked. 

"The first one is the one currently on your tape. It's mostly non-reactive, so its resistance to acids, bases, alcohols, and esters is excellent. Mina shouldn't be able to melt them." 

The girl in question pouted a bit, muttering a "We'll see...". 

"It's not as dense as the second kind, and its tensile resistance is lower, but its resilience is way higher." 

"Resilience?" Toru's voice questioned the word. 

"Not to be confused with resistance, resilience is the ability of a material to absorb energy when it's deformed elastically, and to release that energy upon unloading," Momo responded, taking a word-by-word explanation from her books. 

"In short, it means that the tape is elastic," Nirengeki added, translating the jargon. 

"Yep. Which means it's the perfect kind of tape to stop blunt objects, if you have enough space to let the elasticity do its work. It's not armor, but I can already picture you catching projectiles and sending them back," Izuku chuckled. 

Sero joined him. "I wish, but that idea isn't half bad." 

"Don't start with bullets and you'll be fine. Baseballs should work for now," he proposed. 

Getting to catch bullets was way harder than he could imagine. Good thing most Villains didn't rely on them, being power-drunk on their Quirks. 

"High-density PE instead has a high strength-to-density ratio, it's just as corrosion-resistant, and takes nearly double the heat to melt, around 130 degrees Celsius. It would be the good kind to make traps or ropes out of." 

"Yeah, but I can't make that, can I?" 

"Not yet." Izuku smirked. "As I've said, polyethylene is a mixture of various polymers, all of which you can produce. We could say, for example, that right now you're mostly producing the smaller kind with low n values, with a bit of the bigger kinds mixed in there. With enough work, you could switch those up, getting the high-density you want." 

"Just like that?" Hanta asked, raising an eyebrow. 

"You'll need to produce a lot of it to get a sense of what's right," he pointed out. "But if it's like training a muscle, the results will certainly come. Maybe studying a bit of chemistry may also help you visualize what you need, just like with Momo." 

The girl nodded, offering her help on the matter if needed. 

"I think you'll even be able to choose what kind of tape you want to produce when you've got a handle on it." 

The teen crossed his arms, nodding. "Well, I better start working now then." 

"Yeah, just one last thing: You've always produced one-sided tape until now, so try to move on to double-sided tape. If you can put the adhesive chemicals on one side, what's stopping you from doing it on the other as well?" 

Hanta looked even more surprised. "I had never thought of it like that... Damn, I gotta try that now. Thanks, Midoriya, I can't wait to get some results." 

Izuku sincerely reciprocated the grin. "Just remember to use some products if your skin gets too dry. I think Aizawa wouldn't mind helping you with that kind of problem." 

The 1-B students looked confused for a moment, leading Toru to give them a simple: "Teach has dry-eye and bad sleeping habits." 

"We think Miss Kayama may be helping him stay in shape," Mina quipped. 

On the side, Snipe was trying his hardest to repress a snort. 

"Let's not gossip now," Momo sighed, interrupting the exchange. "Shoda, I believe it is your turn."