Mai's Potential

"When did you buy a writing board?" Maki asks while looking at me pushing the said board in front of her and Mai "And why?"

"Everyone needs a writing board. It's one of those useful things that don't see much in the light of the day but it helps when it is needed... Like a crowbar." I explain.

I bought it I think in the third month that I came to this world... After noticing that my monthly salary was accumulating and I wasn't buying anything. So I went on a small shopping spree.

Bought a lot of cool things, but in the end, I didn't even spend that much... It's hard to spend money. The secret is not buying anything from expensive brands, to this day the most expensive things I bought are my consoles and PC. And some legos... I can't let my inner child die.

 And this writing board was not even that useless of a purchase. It was nice seeing my schedule training and plans written on a big surface.

"Okay, let me explain it in a more detailed way." I say while starting to write some numbers and make some drawings on the board.

Earlier, we talked about Mai's innate technique and I voiced some of my ideas and understandings.

Obviously, her technique is hers, and normally that would be no place for me to butt in, but... I'm a guy from another universe who has a lot of collective knowledge of other people's creative work. One of the reasons I'm creative with my own technique, by the way.

"Regarding Construction, let's say that Mai has a cursed energy amount of 100..." I say while writing the number on the side of a small drawing of Mai.

"Why a 100?" Maki interrupts

"It's just to illustrate the 100%. Mai is the only one that can have a grasp on that. So let's say that this 100 is the total amount Mai has in a day to use in her technique." I say dismissively while I sketch a lot of different weapons on the board. "Continuing, we can say that it costs Mai 10 of her Cursed Energy to make a dagger, 30 to make a short sword, 50 a sword... And it goes on like that."

I illustrate my words on the board, putting the values on the side of each weapon that I am crassly drawing.

"By the way, this value only corresponds to the 'body of the weapon', the weight, the form... Mai would still need to imbue the material with cursed energy to make it a cursed tool. Let's call this amount imbued Attack Potency, or Attack Power... Like in games, not that any of you barbaric women would know about it."

I continue to write on the board.

"I think the amount of cursed energy you imbue during the manufacturing process will determine the Grade of the Cursed Tool. To make things simple let's say that it costs 20 CE, to make a Grade 4 cursed tool and it doubles each time. 20, 40, 80, etc etc... Once again, this is only for the sake of making things simpler to explain. Only Mai can grasp the amount and all factors involved." I stop to point at her for a moment. "Maybe it costs a hundred times more to make a Special Grade Cursed Tool than to make a Grade 4 one?"

I continue my scribbling till I'm satisfied.

"Lastly, adding effects to the Cursed Tool... This is even more open to discussion and I will not waste my time in making a list, but let's say that to add a simple Poisoning/Burning effect would cost something close to 20 CE. And something more esoteric would cost more... In other words, to add a technique to the Cursed Tool, the higher the level of the technique added, the more CE she would have to spend."

Mai created a replica of the Split Soul Katana in canon, so it's safe to say that she can add effects to her manufactured products.

"So there's these 3 things to consider and Mai would need to think how to distribute her CE among them. An example would go like that..."

Normal Dagger – Grade 4

Dagger: 10 CE

AP: +20

Technique: None

Total Cost: 30 CE

"So Mai would only be capable of producing three Grade 4 daggers a day?" Maki asks

"Or one higher-grade dagger... Using 80 CE, I can make a dagger in the second grade." Mai comments "This sounds about right... More or less..." She says after thinking for a while, looking at the board with a pensive expression, probably making her own calculations.

"Let me do another example... You said earlier that your limit is a sword a day, so..." I go back to the board.

Normal Sword – Grade 3

Sword: 50 CE

AP: +40

Technique: None

Total Cost: 90 CE

"Yeah... This is very accurate." Mai comments "Though there are other things to consider..."

"So you can translate her technique to gaming terms, what about it beyond helping her visualize it?" Maki asks

"Well, after Mai discovered her limits, the next step is how to surpass them." I say "Or at least, circumvent them... And I have an idea."

"Some sort of training?"

"I feel that I'm not using my technique as effectively as possible. In the future, maybe I can make swords... while using 10 CE." Mai says while giving a look at my board

"Yeah, that's great... Training is always good, but I was thinking of a more immediate answer." I look at them for a moment before saying "A Binding Vow."

"Isn't that dangerous?" Maki frowns

"It's not risk-free..." I admit

Maki doesn't look happy about it, but Mai asks me nonetheless.

"What type of Binding Vow?"

"Well, do you remember why I said that your technique is a cheat?"

"Yes, a little... Something about skipping the process... And not using time and materials."

"Yep! Those are your advantages. Now, what if you get rid of them? A Binding Vow that balances things a little, making you lose a perk instead of acquiring a drawback, are you two following me?"

"More or less..."

"Okay. Let me give an example... Everyone knows that some techniques require that you say the incantation loudly and make the handsigns. But with training, you can do the same without the need for these complicated processes. BUT!" I raise a finger to make them focus more "If you decide to do the incantations and handsigns even if you don't need them, the technique will end up stronger. Roughly 20% stronger... In most of the cases, at least."

"Yeah, we know about that."

"Everything has a price. The person that trained to shorten the incantations and handsigns paid with his blood, sweat, and time. That's why when he goes back to do the whole process, the technique ends up stronger." I explain one of the basic concepts of Jujutsu Sorcery

I point at Mai and continue "The drawback of Mai's technique is the large expenditure of Cursed Energy. The perks are that she doesn't need to waste time forging her weapons and she can create things from nothing. So what if she puts aside these perks so that she can save Cursed Energy?"

"Like... Using an already existing weapon? Or the material's at least?" Mai suggests

"That too! Imagine that instead of you creating a cursed tool from nothing, you take an already existing katana and imbue it with Cursed Energy?"

"Hm~ Using your... 'game logic'. I use 50 CE to create a katana, leaving me with 50 CE for the extra stuff. In this case, I would at most put the katana in the Grade 3, spending 40 CE." She calculates while resting her chin between her fingers "But if I save those 50 CE using a pre-existing katana, I could very well spend 80 CE to make the katana a Grade 2 cursed tool. It's a huge leap."

She is starting to get it.

"Wait!" Maki suddenly interrupts "Isn't her technique Construction? Wouldn't it… like be... against the basics and principles of her technique if she doesn't 'construct' something?"

A valid concern, maybe Mai can only imbue cursed energy on the things that she creates herself.

"..." Even Mai is frowning while thinking about it

I shrug "My technique is summoning shikigami, and I control shadows and darkness too. There are things called Extension Techniques, after all. I believe she can do it." I smile reassuringly at the younger Twin.

In canon, Mai creates a katana with the effect of damaging souls.

Yorozu who had the same technique also created that thing for Sukuna too, with an electric technique or something.

There's no reason that Mai can't be some sort of "enchanter", it's like a sub-class to blacksmiths.

Maki accepts my answer with a humm but continues

"By the way, what type of materials do people normally use to create Cursed Tools?"

"Well, if this is like a game..." I start, but I'm interrupted by Maki.

"Here we go again..." She rolls her eyes

"...if this is like a game..." I continue undeterred by her "...we would use Cursed Spirit corpses to craft Cursed Tools." But Gege didn't make the world like this

"But curses disappear when they are killed."

"Yeah, but that doesn't stop people from using them. Gojo is gathering the books about Cursed Tools for us, but I remember reading something about artificers of the past capturing curses, cutting them enough to bleed but not to kill, and bathing metals and other materials with the curses' blood. Or simply putting a lot of curses in a place and harvesting the mineral afterward. They would be tainted with cursed energy."

"Nasty..." Mai says in distaste

"This is mild compared with some that use sorcerers' body parts." I say making them widen their eyes in surprise "Curses disappear when they are killed, sorcerers on the other hand..."

I left the rest unsaid because there's no need to continue. They understand how ugly humans can be and how far they can go for something.

"Ah! Another thing before going back to the Biding Vow topic." I attract their attention to stop them from making their disgusted faces "I'm not clear, but apparently Cursed Tool artificers, most of the time ask for the help of other sorcerers to imbue effects or techniques in their work." I know Mai can do it by herself thanks to the example in canon but... "So employing the help of another sorcerer can also be a good way to spare CE."

"Makes sense."

Then I smile smugly "And guess who has a technique that is so versatile that appears to be at least 10-in-1?" I trace my finger around us before comically stopping it and pointing at me

"..."

"..."

The two stare at me in deadpan, because of my antics before Maki sighs.

"*Haah* Are we really made for each other?"

........

"Now that we talked about using pre-existing materials or even an already-made weapon..."

"Do you think I should go blacksmithing?" Mai suddenly asks

"Pfft." Maki bursts out a laugh "Sorry, I can't imagine. Haha."

"I don't know Mai. One of the important things about the compatibility of the technique is your 'likes and dislikes'. Especially in one so versatile like yours." I really can't give an answer to that.

Back to Yorozu, she had the same technique but she used to create a liquid metal, to manipulate it similar to how I manipulate shadows. And also to make an exoskeleton based on insects, and use it like a power armor.

But Yorozu lived in the Heian era. The Golden Age of Jujutsu Sorcery, where everyone was a fighter to survive. Mai doesn't need to be a fighter nowadays.

"Do what you want to do. It's the advice I can give you."

She nods eventually "I didn't think that hard about it, you know? About what I want to do... Most of the time I think about things that I don't want to do."

"..."

"It's a start at least. You can use it as an elimination process or something." I shrug again

"..." Once again she nods, her face showing signs that she is thinking hard about something.

"And learning about things related to your technique is never bad." I say to end the matter before continuing from where I was interrupted "Going back... Mai's other perk is the fact that she doesn't need to waste days or weeks crafting a cursed tool. She can do it instantly."

"When you think about it is really ridiculous." Maki reclines on her chair "You're never caught unarmed, you can adapt to any situation, no other artificer can compete with her in this aspect, she can arm all of Jujutsu Society in what? A year?"

"Not that I will let them know about her for now, but yes."

"The Binding Vow that you talked about must be me not creating the weapons instantly, right?" Mai tries to guess "Like creating part of the weapons separately and then fusing them in something better?"

"That is a good idea. You can do that too." I say. See why it is so important that she thinks for herself? "I was thinking more in your 'restricting your production to create a peak with great momentum'." I try to put in the best way I can

"?" But by the way they tilt their heads to me, it seems I will need to draw again.

Hmpf, and Maki dared to speak ill of my board.

"The thing we talked earlier about using pre-existing materials may not fall under the realm of a Binding Vow, more like a mastery of your technique Mai..." I start scribbling on the board "But this is a Binding Vow. A 100%."

They watch as I draw a calendar to illustrate the passage of time and then numbers adding up in an arithmetic progression.

"Your idea of creating things part by part is good, but I was thinking more about your daily limit, you know? What if you make a Binding Vow saying something like: 'I will not use my Cursed Energy today, so that it can accumulate to be used posteriorly'?"

"This... How would it work? How far could it go?" Mai asks

"Like you're charging and building up CE. Going beyond the limits of your reserves... So I think you would need to be unable to use Cursed Energy in any way." I say with a serious voice.

Similar to how Nanami lessens his output of Cursed Energy during the day, so that he can liberate beyond his normal limits after a certain time... It's his Binding Vow called Overtime.

It's perfect for him, it's even compatible with his personality, and with his likes and dislikes.

Mai also doesn't like fighting, so a Binding Vow that puts her in a position where she is useless in a fight makes sense.

"This is too risky!" Maki speaks almost in outrage "Are you saying to her to not use her cursed energy? This would leave her defenseless!"

"A Binding Vow needs to have a certain level of risk to have a proportional return. Mai can spend one day without using cursed energy and the next day she would have 200 CE to create a Cursed Tool. Again, I don't know the inner workings of her technique... But I guess she would be capable of creating a Special Grade Cursed Tool with one month's worth of Cursed Energy. As she is at the moment she will not be capable of creating a Special Grade Cursed tool without a lot of strain on her body." I remember that she used her life force in canon "This way, the price will be paid beforehand and she will have control over it."

"One month without using cursed energy? Like a normal person??" Maki continues "It's too dangerous!"

"Like how I was previously." This time, it's Mai's turn to interrupt.

"This..."

"I know. Relax." Mai smiles reassuringly at her older sister.

"It's only a suggestion. An idea that was born in my mind from my talk with Mai and her lack of interest in fighting." I say to calm them "Remember that we are keeping Mai's new abilities a secret. The risks lessen this way."

I stand up and walk to them, kissing the top of their heads.

"I will not force anything. I will even leave you two to talk among yourselves." I say before smiling at them and moving away to do my own training "It's only ideas, use the way you like Mai. I will support you in any way."

I, at least, have this much of a conscience. I will respect their wishes as much as I can in their chosen path.

...

- Third Person P.O.V. -

Megumi leaves the room without waiting for an answer from the twins.

This is his way of saying: "I'm not forcing you". Giving them freedom and privacy to discuss this matter.

Mai is still putting on a pensive expression. While she stares at the empty air in front of her.

"Are you really thinking of doing that?" Maki asks incredulously

"It's not that bad..."

"Not that bad?!"

"Calm down, Maki. You're thinking that I would be giving up on using Cursed Energy forever to only create Cursed Tools, but it's not like that." Mai tries to explain "I would only be incapable of using Cursed Energy while I would be... 'charging' to create a Cursed Tool beyond my limits." She explains while stealing glances at the board, looking at Megumi's drawings.

"Hmm, but it would still be dangerous..." Maki says, unconvinced

"Not if I stay holed at home with one of you two protecting me." Mai smiles "You don't get it... I can feel that what Megumi said makes a lot of sense."

"..."

"Now... The worry would be whether it will be necessary to visualize the weapon before, during or after the... charging period. This can be trickier... It would waste precious time. Yes, I can understand why a Binding Vow. The risks..." Mai mumbles to herself, already working to figure out how to apply what she heard today

"You know that you don't need to strain yourself, right? Aren't you the one that doesn't want to work harder?"

"... that was before." Mai says with a distant look, then she turns to Maki with a smile "Now I have things that I want to protect and help. If I can be of use to you two, while not fighting and still being pampered... Haha. That would be the best!" She laughs with a voice full of mirth.

The more she thinks about it, the more she likes it.

Maki can only give her younger sister a helpless smile and a shake of her head, but in her heart, she reached the same simple conclusion Megumi arrived.

She only needs to protect whatever lifestyle Mai chooses.

....

- Megumi P.O.V. -

I walk to a secluded and abandoned spot to do some tests.

I left Maki and Mai to talk with no pressure, but I think they will eventually come around. I, humbly, think my idea was the most fit.

The Binding Vow idea came from beyond Nanami's Overtime, from HunterxHunter. Yeah, like an old Discord friend of mine who was a HunterxHunter fanboy once said: "Nen's power system is so good that it can explain other power systems".

The Binding Vow basically consists of Mai forcing herself into a state of "Zetsu" while she accumulates Cursed Energy. "Zetsu" = Defenseless State, and also for her to not hurt herself by breaking the limits of how much her body can handle.

Now, where will she store the surplus amount? I don't know, maybe in the Cloud or Google Drive... Powers are bullshit man. Things simply work.

And being defenseless will not be a big loss, Mai is not a direct fighter, even in canon she fought with guns at long distances. Even if she needs to fight, she can use the things she prepared beforehand during her defenseless period. Like making ammo, bombs, or whatever.

She can be like Batman, but without the moral block regarding guns.

And if we keep her abilities a secret, the risks will be even lower.

Whatever, no use in thinking too much about it. These things can only be planned after Mai figures out the rules of her Technique and the Binding Vow.

This can also affect her school life, but this is another problem already solved, thanks to Gojo who is the teacher of the first years.

Nepotism for the win.

In the worst case scenario I would need to buy a guardian in the Catalog, like a pet pokémon or something else, but I don't think that would be necessary.

Now, to the training that I came to do here... Let's start with the tests.

Taking a knife from my Shadow Inventory, I unceremoniously cut the palm of my hand.

"..." Well, tried to cut "Sometimes I forget that I'm really durable."

I stare at my unharmed palm for an instant before imbuing a finger with my darkness cursed energy. Going as far as elongating my nail in a dark claw and I finally can make a cut on my palm.

Waiting some time, I pass my thumb over the cut to clean the blood and...

"It's healed already... Without even using the Reverse Cursed Technique."

The Darkness Devil healing factor is really good.

I think even my One Piece body is ridiculous enough to heal me if I eat, right? Or is that only a Luffy thing?

Anyway, the Devils are immortal in Chainsaw Man. They can heal if they drink blood or consume flesh, but the Darkness Devil goes beyond that, he is a Primordial Devil after all.

The other example of Primordial Devil that I remember, the Falling Devil regenerated from pieces in an instant, so I guess I can expect to have that ridiculous healing factor too?

And I think it's even faster at night or in the shadows.

And without taking into consideration that I'm probably immortal, or I will be. Like, regenerating even if my head is cut off. Can someone in this world really kill me? I'm so bullshit.

"I can't test that now because the Template is still in a lower Tier, but..." I grab my little finger and with some effort, yank it off.

Blood gushes out of the wound, but I remain calm to watch if a new finger will grow...

"..."

"....."

"....."

"....."

Yeah... It's not growing back...

I try to put the finger back in the same place and hold it there.

"Oh! It attaches itself without Reverse Cursed Energy."

Alright! So this is the limit of my healing factor... Reattaching limbs. Good to know.

"Wait, is my finger a little crooked? Uhh"

And here I go again pulling it off to reattach it correctly now.

Who would know that it's necessary to pay attention to these details?

"It makes sense, visualization is important when using Reverse Cursed Energy. You understand and know how your body is and you use it to go back to your normal state. That's why it's so hard to use on other people..."

I reattached it incorrectly because my healing factor made my body instinctively latch onto the missing piece.

"And this connects with the training that I'm going to do here... Time to meditate."

Know thyself, or something like that.

You need to understand yourself so that you can use these techniques better. How your body operates, the shape of your soul... These things.

"And especially my Domain Expansion..." I sit down with a big smile on my face.

If I succeed in doing what I'm thinking... My Domain will shock the whole Jujutsu Society! Something never seen before! I will be writing history.

Even Sukuna and Gojo would have to bow down to me in this aspect!

.....

Some days later, I examine a newly made cursed tool created by Mai after she started employing the Binding Vow Breaking Limit Mechanic.

"It looks a little bent, no?" I say lowering down the Katana, making Mai huff.

"I told you..." Maki rubs salt on the wound.

"It's hard! Argh. The bigger the thing to create, the bigger the time span and the more chances to mess up." Mai defends herself while sighing despondently

"Relax, you're only starting." I try to cheer her up

"And katanas are complicated. The curvature and all that, you should've started with a simple longsword." Maki adds

"..."

"True, or maybe you lack... an example." I say remembering that the weapon she created in canon was a copy "We are gonna get some weapons for you to touch, examine, swing, and everything. When you get the feel, it will probably get easier."

This is another thing that I remember from HxH, the Conjurers need to familiarize themselves with the things they wanted to conjure. Once again, my old friend was proven right.

"So you're gonna buy weapons now? How?" Maki asks

"The Internet has everything." Japan has really strict laws against guns, but is kinda lax with cold weapons.

I continue "We can go buy one of each, even a prop should be good enough, but let's try to get the real thing." I say while going back to examine the sword "Meanwhile we can test if Mai can turn normal weapons into cursed tools. By the way, the shape aside, this weapon is really strong. Good job, Mai."

I smile at her and pat her head, making her beam at me. It's essential that she is happy doing that.

....

 "Okay... It's with you now." I say to Mai and move away from her.

She continues to concentrate while keeping her arms in front of her, her hands like she is holding something. Her cursed energy mixes with my dark one, creating something more physical.

"Do you think she will succeed?" Maki asks, after I move away enough to give Mai space.

I shrug not even slightly worried "It will be an experience anyway..." The last thing I want is for Mai to get discouraged if she fails.

"You come up with the craziest ideas." She huffs and rolls her eyes.

We are trying something new today after Mai accumulates more than a week's worth of cursed energy.

Finally, the energy ball coalesces into matter and four objects fall into Mai's hands.

She is sweating a little and panting, coming back from her focused state. Hmm, not as bad as I expected... [Body Tune-up] is working just fine.l

"I think I did it!" She comes at us with a big smile on her pretty face

"Let me see..."

She presents to me four cylindrical hollow objects. With a look, anyone can guess that it is some sort of forearm/ankle protector.

I take one of them, and open it, dividing it into two semi-circles before closing around my left wrist. It's as thick as a smartphone and covers half of my forearm.

"Wow!" My arm almost hit the ground when I was caught off guard after putting it "It's heavy. Perfect."

"Really? They look light to me." Maki takes one of them from Mai's hand

"It only works when you equip them. It's a cursed object after all." Mai explain

Exactly... A cursed object that increases the weight of the whole limb when equipped. The cliche training method of anime!

"Are you sure that it will be beneficial?" Maki still thinks this is bullshit.

"To me, yes." I have a One Piece body after all. "It will work perfectly."

I put the other three around the rest of my limbs and damn... That will be a lot of effort, but I will not take them off for anything.

"Did you decide on a name, Mai?" I ask while feeling the difference in the weight of my body now.

"I don't know, maybe Cursed Training Weights or something? Gravity Weights? Cursed Shackles?" She shrugs her shoulder, uninterested in the name

"Cursed Weights works just fine..." I say. "Though they can really be used as handcuffs to normal people. It's like I have a bus on each limb."

We worked together to create them. Using the Darkness attribute of my cursed energy... Gravity, the heaviness, and all that. So it was possible to make these compacts but super heavy weights.

I smile, thinking that now the Blackbeard Template will be upgraded in no time.

"Zeh~ Carrying a weight like that, I can feel that my battle power is halved at least. The amount of stamina spent, the strangeness of my body not following my mind..."

I gave some jabs in the air to test. While I was working hard to retract my fist, my fist was still there... Not following my instructions perfectly like I am used to.

"Thank you!" I go to rain down Mai's with kisses on her face "I love you!"

"Haha! It tickles! Stahp!" You're not convincing anyone, my dear. You love it.

After showing my appreciation to my girlfriend, I turn to them with a predatory smile forming on my face.

"Now we have a countdown, girls." I laugh "When I get used to it and be like I don't have any weights..." When the Blackbeard Template level up "And Mai produces some more weapons...

"...We can proceed with the taming of the Big Raga, the Opp Stoppa!" 

"...are we really calling him that?" Maki sweatdrops at my words

"What? Is Daddy Raga better?"

"..."

"..."

"...Big Raga it is." They say at the same time in a deadpan.