One day, part-time worker Ryo Kayama goes for an interview for a live-in job. The elegant Western-style mansion stands in a prime location in the city center. After meeting the mansion's owner, Mr. Yasuda, and under the guidance of senior maid Rina Miyauchi, Kayama begins his life as a servant, and immediately falls in love with Mr. Yasuda's daughter, Reika. Several weeks pass, and Kayama, now accustomed to his work at the mansion, hears strange noises coming from Reika's bedroom. Unable to suppress his curiosity, Kayama peeks inside. There, he sees Reika with a lustful, seductive expression, trying to entice a male. Kayama is shocked by the sight he witnesses. The next day, he faces Reika feeling guilty, but she acts as if nothing happened. Kayama feels bewildered, but even after that, he witnesses Reika's strange behavior many more times, yet she continues to act as if nothing happened. Moreover, the maid, Miyauchi Rina, seems to know what's going on. "This mansion hides an unusual mystery."