Akira Yokkaichi teaches Yūji Yagami as his homeroom teacher. He becomes intensely infatuated with Yūji's mother, Nomi Yagami, captivated by her remarkably youthful appearance. This obsession drives him to relentlessly flirt with Nomi, though she remains completely unaware of his intentions. His pursuit establishes him as a rival to Yūji, who also desires his mother's affection. Both Akira and Yūji compete for Nomi's attention, ignoring her devoted and loving marriage to her husband, Yōji Yagami.