Aoi Sanada, the top fighter at Akechi Academy, wears an eyepatch over his right eye to conceal scars from a fire that claimed his father’s life. These injuries, which also mark his shoulder, caused his mother to abandon him and his maternal half-sister, Shino Takenaka, leaving him with a deep-seated fear of rejection.

His life changes upon meeting Megumu Kobayashi, who is disguised as her twin brother, Mitsuru. He saves her from falling off a bridge and, believing her to be a boy, finds himself unexpectedly drawn to her. Even after learning her true identity, his feelings remain, though they are complicated by a phobia that causes him to faint if he comes within two feet of any female—a condition he gradually overcomes through their growing bond.

His family history is complex. In addition to Shino, he shares a paternal half-sister, Azusa Tokugawa. His mother, Yuki, later remarried and had another son, Akane. She died during the 2011 Tohoku earthquake while trying to save others, including Aoi and Akane, and had been seeking to apologize for abandoning him.

Aoi also carries guilt over his fractured friendship with Chiharu Uesugi from middle school. He mistakenly believed he was responsible for Chiharu’s hospitalization due to a heart condition. Chiharu, in turn, resented him for what he perceived as weakness, but the two eventually reconcile after a confrontation where his scar is revealed and Megumu helps mend their misunderstanding.

Aoi and Megumu eventually marry and have a daughter named Ibuki. The character also appears as a romanceable option in a Nintendo 3DS game adaptation.