Class no Daikirai na Joshi to Kekkon suru Koto ni Natta.

High school student Saito Houjo has married his classmate, Akane Sakuramori, the girl who is his biggest rival at school. The two can't seem to get along with each other, but their heart-pounding newlywed life is about to begin!

(Source: Kadokawa, translated)