From Renta!:

As a member of the discipline committee, Akira makes a round of the school every day after class. Even though he'd planned on going home after a quick check, his finding Mitsuru, another second year, coming out of an unused room completely changes his life. Learning that, out of boredom, Mitsuru calls other students to empty classrooms after school to do naughty things, Akira warns him to stop before he ends up getting in trouble. But not only does Mitsuru not heed his warning, he gets even wilder... Can this naughty and twisted friendship develop into something more ?

Read on Renta!