Nao and Yoichi are known as a handsome and beautiful couple in their hometown. After graduating from high school, Yoichi decides to take over the family business and stay in his hometown, while Nao goes to Tokyo to attend university. In addition to Nao, her childhood friend Miyuki, a beautiful athlete, and Kyoko, a good-looking student at the University of Tokyo, live in the same co-ed apartment. However, a strange man, Tetsuo, is also living in the apartment. Tetsuo, a former football player, is known in his hometown as a sex monster and a man full of sex. The narcissistic Yoichi thinks he is no match for any man, but he has no idea that this monster of desire will dominate the whole symbiotic apartment.
奈緒和陽一在老家當地是出名的帥哥美女情侶。但高中畢業之後，陽一決定接手家族生意留在老家，奈緒則前往東京上大學。除了奈緒之外，還有她的青梅竹馬美麗運動員美月以及容貌出眾的東大生京子也同住一棟共生公寓裡。然而這棟公寓裡還有一個陌生男子鐵男入住。鐵男曾是橄欖球運動員，在老家是有名的性慾怪物，滿腦子性愛的男人。自戀的陽一自以為不會輸給任何男人，完全沒有想到這個性慾怪物將主宰整棟共生公寓。
