Shiki possesses the "Mystic Eyes of Death Perception", a supernatural ability that allows the user to see the "death" of everything in existence and kill the object by destroying its "origin". As a child born into the Ryougi family, she is raised with a male "yang" personality and a female "yin" personality. However, one day she runs into an accident that puts her into a coma.

After recovering after two years have passed, Shiki discovers that she can no longer feel her male personality and assumes that he died because of the accident. However, now she feels a detachment from her memories and identity, no matter how she tries to recover herself. With her ability and the clever Mikiya Kokuto by her side, her life takes a dramatic turn of events, plunging her into the mysterious world of the supernatural.