Class de Otoko wa Boku Hitori!?

When a formerly all-girls school goes co-ed, Machida-kun ends up as the only guy in his entire class. That premise alone sets the tone for everything that follows. His classmates, including the forward Rio Yamakawa and the teasing Mao Horiuchi, have basically zero experience being around male peers, which means Machida spends most of his time flustered, cornered, or caught in situations he absolutely did not sign up for. The humor comes from that awkward energy, a shy, inexperienced guy trying to keep his head down while the world around him refuses to cooperate. T-Rex keeps the animation lively, with expressive character designs and a bouncy soundtrack that matches the comedic rhythm pretty well. It is a single OVA episode adapted from the manga, so you are getting a focused slice rather than a full story arc. If you enjoyed the fish-out-of-water social comedy in something like Hitori Bocchi no Marumaru Seikatsu, or the reversed-environment discomfort from Otome wa Boku ni Koishiteru, this hits a similar note, though with a noticeably more adult edge given its hentai classification. Going in knowing what it is matters here. It is not trying to be a deep character study. It is a short, comedic, adult OVA that leans into one very specific situation and runs with it.