Masamune-kun's Revenge

As a child, Masamune Makabe was overweight and repeatedly bullied by Aki Adagaki. The humiliation leaves him determined to transform himself and eventually take revenge on the girl who treated him so cruelly. He spends years pursuing an intense program of self-improvement with that goal in mind.

By the time he transfers to Aki's school, Masamune is handsome, popular, athletic, and academically successful enough that she does not recognize him. He now has the opportunity he spent years preparing for: get close to Aki and humiliate her in return. Yet carrying out a carefully imagined revenge proves more complicated than planning one, especially when old feelings and a new school life begin interfering with the simple satisfaction Masamune expected.