Katsu!

Satoyama Katsuki and his best friend Kawakami Kyouta, both age 15, enrolls in Mizutani Boxing Gym to get close to their tomboyish crush, Mizutani Katsuki, whose father owns it. However, Satoyama soon finds out that she is distant from her father. Worse, it turns out that she hates boxing.

In a sparring match, everyone including Mizutani soon discovers Satoyama's hidden yet unpolished skill in boxing. Satoyama soon learns that Mizutani is really in love with boxing, but disdains it because its a man's sport of which she cannot join. Mizutani then takes it upon herself to be Satoyama's trainer/manager to reach the championship belt. Satoyama complies to be closer to his crush.

As the story progresses, we soon find out that Satoyama has a hidden past and lineage, one that would give him the necessary skill and talent to be a legendary oriental pro-boxing champion.

(Source: Wikipedia)