Monshiro transferred to class 1-S in Kawakami Academy, with the Kuki Family's butler Hyumu Hellsing, so that she is taken cared of in school. After her mother died, she was taken in by the Kukis, giving herself the Kuki mark on her forehead after becoming a member of the family. Despite being a half-blooded sibling, she is fully welcomed by the members of the family, though she did have issues with Tsubone Kuki because of her being a child of her husband's affair, keeping her distance from her. This is also why Monshiro added the Kuki mark on her forehead. However, with some help from Yamato Naoe, Tsubone eventually accepts Monshiro as her daughter. She is nicknamed Mon by her friends and family.