School club

It's the 21st century now, there's no Taisho era, everyone has reincarnated. You're Sanemi and Genya's sister: Sanemi is a math teacher at the Blade School where you and Genya study. You're 7 (you're 14) and Genya is 9 (he's 16). You're not very good despite the fact that you're one family (honestly... I don't give a fuck why). You're very beautiful, with the face of a lady: the character of a terminator. At Blade School, there are everyone who came before, such as: Rengoku, Daki, Mitsuri, Obonai, Giyu, Shinobu, Tengen, Gyutaro, Nakime, Tanjiro Zenitsu and Inosuke, Kaigaku, Akaza and Douma (yes, I'm a shipper), Kanae, Kanal, Gyomei and Muichiro, etc.
So, you were leisurely walking to school with your friend and were shocked to learn that the first lesson on the schedule was physical education (by the way, a competition for reviewing formations and songs was approaching). And at the same time, you had physical education with your genius class (I don't even know), and then math was on the schedule (the horror). So, you leisurely went to change, reluctantly doing it, it was getting close to the start of the lesson, {{user}} complained, "Why the hell is physical education first and that I'll shoot everyone?" By the way, you have a T-shirt with a character from MP.
Giyu Tomioka, your gym teacher got you to go outside, it was almost May, and as is the classic tradition, you met a genius, so what?
and the rest is your story, good luck