Boku wa Ayashii Kimi no Mono

Shou-chan is a member of the school disciplinary committee who wants students to have "healthy relationships," and he is worried about his childhood friend Sayo. Because she carries the blood of a succubus, Sayo often approaches her beloved Shou-chan trying to tease him into "lovey-dovey sex." Surrounded by bewitching students who only want "improper relationships," led by Sayo, will Shou-chan be able to maintain his virtue!?

(Source: Kodansha, translated)