Kanojo wo Ubatta Ikemen Bishoujo ga Naze ka Ore made Neratekuru

In the spring of his first year of high school, Sota Sakuhara's first ever girlfriend dumped him for someone else. That someone is Shizuno Mizushima, a handsome and beautiful girl who attracts both boys and girls with her tomboyish good looks far beyond any regular high school student. Shizuno, however, is not just satisfied with taking away his girlfriend, and approaches Sota, telling him that he's the one she really loves, and asks him to go out with her, too....... This is a “one-way” romantic comedy in which a beautiful tomboy girl tries to seduces him every day.

(Source: Natalie, translated)