Genzan-san no Meirei wa Zetsu! Tai!!

Synopsis

One day, Togawa, an ordinary high school boy who wished he was more popular, gets caught in a compromising position by his crush, Genzan-san. In an empty classroom after school, he was using her worn underwear to ○○○○… Ever since then, he is forced to be “absolutely obedient” to Genzan! His high school life as a slave has begun! (Source: Nihonbungeisha, translated)