Kwon Yuri, Seo Joo Hyun, Aiden Liu Yiyun, Kim Taeyeon, Ok Taecyeon, Kim Hyoyeon, Choi Sooyoung, Kim Kibum, Lee Taemin are 9 boys who live together their parents are buiseness partners of eachother and are on buisness trips all the time. Jessica Jung Sooyeon, Krystal Jung Soojung, Im Yoona, Tiffany Hwang Miyoung, Sunny Lee Sunkyu, Ellin Kim Miyoung, Meng Jia, Suzy Bae, Nicole Jung are 9 girls who lives together for the same reason as the 9 boys.