One rainy night, Myeong-joo hits Yoon-bong in an alleyway. Myeong-joo, embarrassed, takes Yoon-bong to her sister's house, and Yoon-bong wakes up thanks to the sisters' sincere care, but has no memory at all. Yoon-Bong who lost his memory, is deceived by her older sister Ji-seon he was her boyfriend and starts to fill her lust by having sex every night. Kang-tae begins to actively seduce Min-jeong....