Kyuuso wa Cheese no Yume wo Miru

When Kyoichi Otomo's wife starts to suspect that her husband is cheating on her, she hires a private eye, Imagase, to investigate him. However, not only does Imagase know Kyoichi from college, but he’s been nursing a crush on the man for years. Imagase gives Kyoichi an ultimatum: if Kyoichi wants to keep his cheating ways under wraps, then he has to give Imagase something in return. Imagase's demands start with a kiss, but as the two men become entangled in each other's lives, it soon becomes clear they each might want more than the other can give.

(Source: Seven Seas Entertainment)