Aira Yukimura, a 17-year-old schoolgirl in a futuristic society, starts diving unexpectedly into different lives — which she learns are her own past and future reincarnations. Each journey reveals parts of her soul — innocence, strength, darkness. But someone else — a mysterious man — holds similar powers and uses them to twist lives for his own gain. With the help of her classmates and new memories, Aira must face him and herself — before the cycle breaks forever.