The last winter of their high school life.

Kazuhara feels lost, faced with entrance examinations and graduation. He is told to become independent and live by himself. He tries to find a room, but he doesn't get many hits. Seeing him in that situation, his childhood friend, Takanashi Shiori, proposes that he live with her.

He thinks to himself that he was told to live alone, but after getting consent from his parents, he ends up living together with his childhood friend. With that starts their 1-month cohabitation. He's sure that nothing will happen since they've known each other for so long. But, as they start to live together, he starts to see her more and more as a woman...