First day of teaching(1)

Nao saw that smoke came out of Chiaki's head as if her brain had been fried due to the overwhelming information Nao gave within a short time. She dropped her head comically on the table as she fainted.

"It's quite lengthy..."

Her eyes glazed over and a small trail of drool escaped from the corner of her mouth as she muttered. Nao, who had been enthusiastically sharing his knowledge, now stood frozen in shock, his mouth agape. The room fell silent as he stared at Chiaki, unsure of how to react to her sudden collapse.

Nao grabbed a nearby fan and began fanning her face, hoping the cool breeze would bring her back to consciousness.

"Don't be overdramatic, wake up!"

Chiaki's eyes fluttered open, and she let out a groan. Slowly, she sat up, rubbing her temples as if trying to massage away the lingering effects of the information overload.

Nao found himself unable to suppress his annoyance towards his sister's conduct. She feigned unconsciousness after merely a few moments of his speech, intensifying his irritation.

"I hate lessons, you know?... you should make it shorter..."

"You better get used to listening to my lectures because I'll be teaching you academic lessons after our school finishes from now on."

"Huh?!"

Chiaki was taken aback when she heard her brother's words, causing her mind to go blank. She never anticipated that her younger brother would attempt to teach her on his own. How could he, being three years younger than her, possibly teach her anything?

Nao had just started the second year of middle school this year, while she was already in her second year of high school. The confidence shining in his eyes as he claimed he could teach her raised numerous doubts in her mind. It made her wonder just how intelligent her brother truly was.

Nao's lips curled up into a smirk as he observed his sister's bewildered expression. He was well aware that his sudden announcement had caught her off guard.

However, he was dead serious about his intention to teach her. He didn't want his sister to become even more spoiled than she already was. This time, he was determined to put an end to her foolishness and personally guide her towards a more proper life.

If she dared to refuse his offer or attempt to deceive him, he wouldn't hesitate to involve their parents. Chiaki was also aware of this, which explained her current state of conflict.

Without giving her any more time to ponder, he continued speaking with a sly smile on his face and a reassuring tone in his voice.

"No need to stress about my studies, I've already completed my syllabus. Now all I have to do is review everything when exams approach. From what I recall, you can easily excel in subjects like Japanese language, Social studies, Arts, Music, Physical education, and Practical arts as long as you put in the effort. However, the real challenges lie in Mathematics, Science, and Foreign languages. Particularly, nee-chan struggles with foreign languages. But don't worry, once I've mastered everything from your textbooks, I'm confident I can teach you. Shall we begin immediately?"

Given his status as an adult who has regressed rather than a child, he possesses extensive knowledge and exhibits a remarkable ability to grasp various subjects swiftly.

Due to his familiarity with various subjects, he quickly grasped everything compared to his peers. Since has accumulated experience as an Asian student and possesses a mature intellect, it would be regrettable if he were unable to acquire new knowledge. 

When he asked his sister if she was ready to start, Nao seemed like a demon in her eyes.

"Right away?!"

"Yep, I'll check out your books while you handle the dishes. As soon as you're done, I'll start teaching you immediately."

Chiaki is responsible for washing the plates and dishes as part of their regular routine, while Nao handles all the cooking.

"Eh?... for real?"

"For real."

"Shall we start my study from tomorrow?"

"Nee-chan, do you want me to call our mom right now?"

Despite the gentle smile on Nao's face, his eyes did not reflect the same warmth. His entire demeanor exuded a chilling aura, suggesting that he would not accept her refusal. Chiaki struggled to come up with a solution to dissuade Nao, but her efforts proved futile.

After a few desperate moments, she resigned herself to her fate with a dejected sigh and proceeded to wash the dishes and plates. Meanwhile, Nao made his way to his sister's room and began reviewing her math subjects.

Since he possessed the ability to teach his sister any foreign language without the need for further study, he decided to tackle her next major challenge - mathematics.

Totally 14 subjects were contained in her syllabus such as statistics, Area, Surface area, Capacity, Weight/mass, Volume, Trigonometry-ratios, Pythagoras, Trigonometry-compass, Trigonometry-elevation, Trigonometry-practical, Scientific notation, Coordinate geometry and Trigonometry rules.

He initially decided to focus on studying trigonometry ratios as the majority of his course materials were trigonometry-related and primarily focused on the application of specific angle functions to calculations.

He quickly grasped the concepts and began solving numerous problems when his sister entered the room.

Chiaki initially had doubts when Nao claimed he could easily grasp her subjects, but she was left astonished when she witnessed him effortlessly solving every mathematical problem.

As she observed her brother, she couldn't help but question her own life. Despite her dislike for studying, she found herself compelled to do so as she witnessed her brother's unwavering dedication for her sake.

Nao began by explaining the very basics, such as angles and their functions, in order to help his sister quickly grasp the concepts. Over time, Chiaki started solving problems on her own after receiving repeated guidance from her brother.

It was at this point that she truly realized the extent of her brother's brilliance.

Unbeknownst to Chiaki, she spent more time with her brother than she had realized. It was only when they noticed a wall clock that Nao finally put their notebook away.

"Phew, finally... it's over..." Chiaki said with a relieved tone as she saw Nao putting their notebooks away. She stretched her arms as she sat on her bed with a tired smile on her face.

"Yeah, you really outdid yourself this time, nee-chan. Thank you for all your efforts."

"Hm?!"

Nao couldn't help but smile as he saw how hard his sister had worked this time. He affectionately placed his right hand on her head and gave her a gentle pat, softly rubbing her beautiful golden brown hair without even realizing it.

 ***

Author's note:

I would like to express my deepest appreciation to Grey Knight Lord, Tempest1618, Manuel Chavez, WonderingAbyss, David Aderoju, GigaChad, Sir_dood134 (Mr. Andrew), Masutatai, Ceyhun Cagirici, Austin, Copinsa, Brandon Alberto Plata Espinoza, Nawaf Rashed, PhantomNite, Darkaito 121, Jaydon Tonkin, Eric, and Devor for their invaluable support and contributions to our fanfiction. Your sponsorship and encouragement have had a profound impact on our creative endeavors, and I will forever treasure your presence in our fanfiction journey.

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