Maya and Yu, a good-looking couple who envy the surroundings. The two have recently started living together and have fostered deep love. One day ... Yu's younger sister, Kokoa, came to Tokyo from her parents' house. Yuu is pleased with the reunion after a long absence, and Maya cannot hide the joy of seeing Yuu's sister for the first time. However, Shina had a certain spirit. "You want to take away people's things." Shina steadily begins preparing to take her sister's lover, Maya, to sleep. And the day of decisive action will come ...