Reina, a female college student, begins a new life with her stepfather after her mother remarries. Reina has come to Kokoro her very kind stepfather, but one day, everything changes. She witnesses her stepfather sneaking into Reina's room and devouring her underwear. However, she doesn't want to see her mother sad. From that day on, Reina distances herself from her stepfather, but her grandmother falls ill and her mother has to go back home for a while. Then, when Reina tries to escape to a friend's house, her cunning and perverted stepfather gets in the way...