Ryoukan-san wa Tokidoki Ii Ko.

Kouki comes across as the perfect student, but deep down he has a penchant for torture that he keeps in check. However it doesn't take long for Tobari, the new superintendent, to learn his secret! Tobari shows his conniving side and has Kouki help him with his work in exchange for his silence. Kouki's desires start to overwhelm him, and soon he develops a need to dominate Tobari...

A dormitory romance that begins with the tying of a different knot!

(Source: Renta!)