She along with Goetia, Galahad, Galahad (Alter) and Tachie are the brothers of Mash and the antagonists of the novel.

The protagonist is Ritsuka (the gender is your choice) and the story is a romance between Mash and Ritsuka that develops throughout the novel with Mash's brothers (except Galter) being the antagonists who try to ruin the romance. She is Mash's older sister and a woman who hates romantic relationships, is promiscuous and treats her partners like toys, her endings consist of NTR and are one of the darkest and most unpleasant in the novel.

After obtaining the True Good End of Mash's route, the routes of the rest of the brothers will be unlocked. In the route of the older sister it is revealed that in the past she was a sweet and loving person who had a partner whom she loved very much but who unfortunately cheated on her and ended up publicly humiliating her, this being the reason why she hates romance.