Inu mo Hashitte Koi wo suru

Atsushi, a student studying for his graduate degree, has a very loving boyfriend, Yoritomo. Atsushi moves in with Yoritomo to finish his thesis. Yoritomo, who's prone to very naughty fantasies, is thinking of different ways to enjoy his new roommate, but his brother, Katsuyori, shows up unannounced... which is bad news for Atsushi!!! Also included is a story about Atsushi's friend who seduces Katsuyori.

(Source: Renta!)