Butterfly Bone on Your Lips ~Butterfly Rouge~

Software engineer Chiaki Yanagishima is dating the owner of the club "Butterfly Kiss", Masatsugu Shibanushi. Known as "Osho" or "King", Masatsugu is constantly surrounded by women. As he continues his relationships with numerous other women, Chiaki's heart and body begin to wear thin. Every time he tries to complain, Masatsugu takes him roughly, and Chiaki just can't refuse... However, when talk of a transfer comes his way, Chiaki finally decides to break things off with Masatsugu... but will he let him?

(Source: MangaPlaza)