In a world where everyone is born without a gender and bodies shift toward the one a person wants around age twelve, Hinase has reached eighteen still unchanged and content that way. Gender never mattered to them, and with childhood friends Ritsu and Shiori at their side, they expect their final year of high school to go on as always. Then both friends confess on the same day. Ritsu is cheerful and cute, Shiori is thoughtful and tall, and Hinase has never felt romantic desire, so they have no idea how to answer either one. As adulthood approaches, time is running short, and Hinase must soon decide whether to become a boy or a girl. The story is a quiet drama and romance about identity and growing up.