Koizumi-sensei wa Midasaretakunai

A teacher who was bullied in the past, Koizumi plays the role of a good-looking and extroverted teacher to protect himself. Because of that, he's very popular with female students. In truth, he is a gay introverted virgin. Being transferred to a school in the countryside, the unfamiliar environment and stress of lying about his true character make him want to cry every day. On top of that, his intimidating and hard-to-handle colleague, Wanibuchi, finds out who he really is. For some reason, however, Wanibuchi likes him and invites him out every free day they get. He even goes as far as giving him a lewd kiss?! A totally inexperienced Koizumi keeps being teased—?!

(Source: Kadokawa, translated)