Sex Girl 9: Three people clean up the house for Min-soo who is new to the house. Yeong-cheol, who has become close friends while living in one house, is obsessed with Seo-yeon because he does not like Min-soo. Seo-yeon knows the relationship between the two and has a strange confidence watching the fight between the two. The fierce fight between the two men trying to win the relationship with Seo-yeon before Min-soo enters the house! The story of the unknown end is just beginning.