Masamune-kun no Revenge follows Masamune Makabe, a high school student determined to turn a painful childhood humiliation into the perfect act of payback. Years earlier, the wealthy Aki Adagaki rejected him cruelly because of his weight, leaving him with a grudge that shapes how he sees himself and everyone around him. After reinventing himself as a handsome, polished, and intensely self-assured teenager, Masamune returns with one goal: make Aki fall in love with him, then reject her in return.
Once the plan begins, however, school life becomes far more complicated than Masamune expects. As he spends more time around Aki, ordinary classroom routines give way to awkward encounters, unexpected emotional shifts, and secrets tied to Masamune's past. What starts as a revenge scheme slowly turns into a romantic comedy about pride, insecurity, personal growth, past trauma, and the unpredictable ways attraction can alter both the pursuer and the pursued. Masamune is left to confront a simple but uncomfortable question: will revenge finally satisfy him, or will chasing it only reopen wounds he thought he had buried?