Our main char falls with a big bang for the new beautiful transfer student Natsuki. While he keeps it in himself, he finds out that Natsuki is quite the rebel who does what she wants, she's strong enough to break his mean senpai's arm and send him to the hospital, and she's the one who just broke his bass guitar. He still follows her around and finds out that she's quite nice but tries to distance herself from others. The reason is that she's getting married as soon as she graduates. This is also the reason why no one really punishes her for doing the stuff she does in school.

Still our main char falls more for her and it seems like the love is mutual?

The hindrances in this story at the end of first chapter are the marriage and the mean senpai who falls for Natsuki after hearing her sing in an instrument shop.

(Source: MU)