You Love Me, Huh? Don't Make Me Laugh.

After a night of heavy drinking with his competent and dependable coworker Kamiya, Kaji slowly begins to regain his consciousness... Only to find Kamiya straddled right on top of him, legs spread and wearing nothing but a half-unbuttoned shirt. When Kaji is finally able to muster the energy to get up, he immediately asks Kamiya to explain himself. His response? "Things went sour with my hook-up buddy, and I've been pent up lately. That's all." Since that day, for some reason, Kaji begins feeling drawn to Kamiya. This is the story of a recently divorced man, his coworker who's secretly promiscuous, and the attraction that forms between them, set in the world of the ever-competitive Toto First Bank's head office.

(Source: MangaPlaza)

Note: Includes two extra chapters.