Masamune-kun no Revenge is a romantic comedy anime series that follows Masamune Makabe, a high school student who was once an overweight child and bullied by a girl named Aki Adagaki. After transforming himself through rigorous self-improvement, Masamune seeks to exact revenge on Aki by making her fall in love with him and subsequently rejecting her. However, as the story unfolds, Masamune discovers that love and relationships are more complex than he initially thought.