Ano Ko wa Itsumo Boku ga Suki

Ushio is the prince of the girls' high school, with her beautiful looks, academic abilities, and athletic talents. Contrary to her appearance, she is a young girl who dreams of marrying her childhood friend and boyfriend, Yuu. One day, her cousin, Souichirou, a high school teacher, appears before her. Souichirou, who has known Ushio since childhood, finds out about her relationship with Yuu and her career aspirations, and takes a certain action...

(Source: Shueisha, translated)