NATSUKA often visits her cousin Mitsuki's house whenever there's an occasion. Being an only child, NATSUKA looked up to Mitsuki like a sister. Today, she's going to Mitsuki's house again. Recently, her mother remarried, but her new stepfather has been making advances towards NATSUKA, leading her to develop a distrust of men. As she confides in Mitsuki, they soon enter into a forbidden relationship... "You know, girls can have sex with each other too?"
