Takuya lost his mother at a young age, and his father, Kazuhiko, remarried a woman named Junko—who was significantly younger—when Takuya was in high school. Kazuhiko passed away from illness four years ago, and Takuya had been living alone with Junko ever since. One day, Takuya brought his fiancée, Misaki, home to introduce her to Junko...
