Masamune-kun's Revenge.

As an overweight child, Makabe Masamune was mercilessly teased and bullied by one particular girl, Adagaki Aki. Determined to one day exact his revenge upon her, Makabe begins a rigorous regimen of self-improvement and personal transformation. Years later, Masamune re-emerges as a new man. Handsome, popular, with perfect grades and good at…