Rika has admired her cousin Mao like an older sister ever since they were children. As she grows older, Rika begins to confide in Mao about things she cannot discuss with her parents. Mao, who came out at eighteen, now enjoys her romantic and sexual life openly with other women. Watching her, Rika feels a mix of envy and fascination, and gradually starts to see Mao as someone far more special than before.