Mizuki, the older sister who is currently working as an office worker, cares very much for her younger sister Nana. Nana has a boyfriend, Masato, with the intention of getting married. One day, Mizuki is visited by a man named Kita. Kita is the manager of a fashion health club where Mizuki once worked for a month, and he approaches her with ulterior motives. Kita is malicious and not only pursues Mizuki, but also extends his poisonous fangs to Nana. Eventually, he pins down the sisters in front of Nana's fiance...