Junai Tokkou Taichou!

Chiemi Yusa's high school record is far from perfect. She's already been suspended twice for fighting, and she's not even half-way through her first year! In danger of getting expelled for starting yet another brawl, her teacher approaches her with an unexpected offer: get her classmate Akifumi "Deranged Devil" Hirata, the nastiest fighter in the whole school, to clean up his act, and her record will officially be cleared. Reluctantly she accepts, and immediately goes on the attack. But as she's waiting for him to retaliate, she discovers that he has more in store for her than just a fight!
In Love Attack, you'll find a rollicking brawl of a good time as the roughest guy and girl in school get themselves into trouble—and find themselves in love.
(Source: Tokyopop)