Shanai Koiwazurai: Ore, Kaisha no Kouhai ni Ikenai Koto sareteimasu

Satsuki and Kippei are your regular coworkers. Kippei is Satsuki's subordinate and listens to his requests like handing out papers and... kissing him?! Correction: Satsuki and Kippei are NOT your regular coworkers. Their physical relationship started thanks to a mix-up with hotel rooms on a business trip, and since then, they have fulfilled each other's carnal needs and acted like friendly coworkers at the office. Satsuki starts wanting more with Kippei but decides it better to stay as they are to avoid ruining their relationship. But will they be able to stay work partners for long?

(Source: Fantasista Inc.)