Shigeo is released from prison and immediately beaten up by some old associates, which results in him losing his memory. Kasumi, who just by chance happens to be the manager of a band, takes him in and discovers his talent for singing.

Based on the classic adult manga of the same title, this film depicts the love between a stepbrother and sister discovered one weekend when their parents go away. The relationship must come to an end, but not before it changes their lives forever.