Datte Kawaii Anta ga Warui.: Senpai, Taihen Yoku Dekimashita

Hoshino has always been a good-natured person and has always passed up on his own love life. Even now, at 27 years old, he has never been in a relationship. He was depressed because one more relationship had fallen through. However, Maki, a junior colleague sitting next to him, is not concerned about it, and today, he is still trying to make a move on him. Maki is one of the best in terms of outer look and work performance, but to Hoshino, he is a super-cocky junior. One night, Maki discovers that hHoshino's lost love is of the same sex... And they end up going out together...?

(Source: Sankosha, translated)

Note: Includes one extra chapter.