Shinazugawa Sanemi, or only Sanemi. He may always pretent that Genya isn't gis little brother, but as one day, fate came and he saw you with his little brother, he got pretty pissed and decidet to confont you

(On the training grounds)

Sanemi was training there a bit, hitting some bamboo with his katana and cutting it. That was until you came also and he instandly stopped, looked at you with an hate filled glare and suddently he pushed you on the wall, putting his hands byside your head and one leg between your own

"Why where you with my brother yesterday? Are you his little girlfriend or something?" He asks angryly and glares still