Masamune-kun's Revenge.

"I've returned to this town for revenge!" Eight years ago, Makabe Masamune, a weak and chubby boy, was harshly rejected by the beautiful Adagaki Aki. Now, he's lost a ton of weight, changed his name, and returned as a handsome teenage boy... all to make the "Brutal Princess" Aki fall in love with him so that he can reject her just as harshly as she did.