After her parents died, Mirai, an office worker, lived with her brother Keisuke in the house they left behind, helping each other out. But one day, her brother left the house after a certain incident. Mirai has been waiting for her brother to return to her spacious house. Mirai is still a virgin. Every night, she imagines it, running her fingers over her and letting out moans. Mirai has also found a boyfriend. But when the time comes, her body is unable to accept him...