NATSUKA always visits her cousin Mitsuki's house. For the only child NATSUKA, Mitsuki has always been like an older sister. Today, she walks the familiar path toward that house once again. Recently, her mother remarried, and her new stepfather has begun showing inappropriate interest in NATSUKA, leaving her distrustful of men. Confiding in Mitsuki about her troubles, their bond gradually evolves into a forbidden relationship. The two exchange shocking words: "Women can make love to each other too."