Teisou Gyakuten Sekai de Yuiitsu no Otoko Kishi no Ore, Onna Kishi Gakuen ni Nyuugaku shitara Nazeka Eiyuu Atsukai sareta: Zetsurin Skill de Harem Musou

In a matriarchal world where women dominate and men are treated as lesser beings, Kureto was cast aside at birth for the sin of being born male. He scraped by as an orphan, unwanted and powerless—until the day his unique skill awakened. A "supreme virility" skill that strengthens him with every act shared with a woman.

Under the guise of "training" with his dorm caretaker, Kureto masters his newfound power, achieving strength no man should possess. When he's accepted into the elite Knight Academy—a school meant for noble-born women—he sees a chance to change his fate. To become an honorable knight, to reclaim his dignity, Kureto will fight—both in the arena and between the sheets—against the very women who once looked down on him.

(Source: Futabasha, translated)