Itsuka kaede, a 19-year-old girl from Itsuka house, has a twin sister. But for some reason, it made a mistake with her sister at a young age. She now lives with her brother Itsuka Shido, but she hasn't been with her brother since childhood. Her parents were divorced. So she had to go with her mother. Causing her to secretly come to her brother periodically without her parents knowing. All along, she was taken care of. Much attention was given to her brother. As a result, she began to feel more and more in love with her own brother. She became extremely jealous when she learned that her brother had messed with another woman. This caused the women around her brother to start to panic and began to gradually disappear. Until one night, she ran away from her home to be with her brother. to keep her brother from having any other woman besides her.