Ai ga Matteru

From Yaoi Is Life: There's Kiyohito, who continually cheats in whatever relationship he is in. One day, while he was sitting at a bar, a man named Hisashi comes stumbling in. Hisashi's got less morals than Kiyohito, but despite being a crazy guy, Kiyohito can’t bring himself to hate the guy. When they are together, everything feels good...?!