After being separated from their parents in childhood and left as orphans, Kyōko and Namiko were raised with the love of their aunt and grew into beautiful women who attracted the attention of many. Yet the chaste and gentle elder sister, Kyōko, somehow came to be called the “Iron Maiden.” When Namiko asked her about it, Kyōko would only say, “No matter what the world says, you are the only one I trust.” There was a reason for Kyōko’s transformation. One night, after seeing off Shinji, who had come to visit their ailing aunt, a man named Hayakawa assaulted Kyōko on her way home. Wounded, she chose to bear the title “Iron Maiden” herself. She also resolved in her heart to leave the inheritance of her aunt’s house to her younger sister. But then, Namiko appeared before Kyōko, intending to introduce a suitor. To Kyōko’s shock, it was none other than her rapist. Kyōko resolved to protect her sister at all costs.