Doutei Otaku to no Sex ga Ii Hazu ga Nai

Makoto Mitsuya is an economics student living in a dorm. After his roommate is hospitalized, he indulges in his otaku hobbies to the fullest while living alone. However, his new roommate, Ken Hayami, turns out to be the complete opposite—a flashy party animal with a totally different personality and appearance from himself! Frustrated by their clashing personalities and Hayami's annoying behavior, Mitsuya initially holds a grudge, but slowly begins to open up thanks to Hayami's attempts to get closer.

One night while drinking together, Hayami teases Mitsuya for being an inexperienced virgin. Annoyed by the teasing, Mitsuya impulsively pushes him down. But when Hayami reacts with obvious pleasure, Mitsuya gets carried away—and the two end up having sex...?!

(Source: Takeshobo, translated)