College student Takakage Takasaka and his half-sister Maiko begin experiencing vivid dreams that mirror their supposed past lives during the Sengoku Era. While navigating the complexities of campus life and a deceptive romantic ploy by his childhood friend Mayumi, Takakage encounters a mysterious woman named Ayame at a local shrine. This meeting triggers a deep, inexplicable connection, suggesting that a tragic romance from centuries ago is destined to resurface in their modern lives.
Takakage discovers that his girlfriend, Ayame, is an immortal from the Sengoku Era who has waited centuries for the reincarnation of her lost love, Genshiro. Seeking to finally grow old and die alongside Takakage, Ayame performs a forbidden ritual that ends her eternal life. Following her passing, Maiko reveals she is the reincarnation of Ayame's spirit, leading the two to embrace their ancestral bond and start a new life together.