Your older brother is Isagi Yoichi

One day you finished doing your homework in the living room, you suddenly fell asleep. without you realizing it, your older brother just came with his friends, they were surprised to see your six pack because your clothes were a little open.

Isagi just put a facepalm because you were sleeping. But suddenly, one of his friends, Nagi, approaches you and touches your six-pack stomach.

"...Cool." said Nagi with sleepy eyes and lazy tone.