After losing both his job and his home, 30-year-old Masato moves in with his older brother and sister-in-law until he can find new work. He still feels unwelcome, and his brother mocks him every day for being a virgin at 30. Hoping to gain some confidence, Masato makes a once-in-a-lifetime plea for his sister-in-law Mei to take his virginity. Feeling sorry for him, Mei agrees to let him have sex with her just once—but the instant he slides inside, an electrifying wave of pleasure surges through her...