Masaya Mizuhara is Tomoya Mizuhara's biological father, who experienced the loss of his first wife — Tomoya's mother — during the boy's early years. After a period of time, Masaya remarried, wedding Yuko Mizuhara, the mother of Ichika Mizuhara. This union positioned Masaya as Ichika's stepfather and established a blended family where Tomoya and Ichika became step-siblings.