A story about a girl named Kyouko Ichjio, the twin sister of Haruhiko Icijo, decides to come back home to her brother after more than 5 years. Back at home, she meets three girls named Mai, Koito, and Reina. So far everyone that has met Kyouko, knows her as Haruhiko's twin sister that got into some incident that no longer made her human. But is that really the case? Will Kyouko be able to keep others around her once they learn the truth about everything?