Takaya is a lonely, proud, fiery-spirited 17-year old high school student who has suffered from a violent father, was separated from his divorced mother, and is living in Matsumoto. Bizarre ghostly incidents start to happen in Matsumoto affecting his best friend Yuzuru. When he meets a mysterious man called Tachibana Yoshiaki, Takaya finds out that he is the reincarnation of Uesugi Kagetora, the leader of the Uesugi Yashashu. It is his duty to fight malevolent ghostly troopers and the restless spirits of ancient lords and warriors.

It seems that here in the twentieth century, all the fierce major warlords and heroes of the Sengoku Period (the Civil Wars) have been reborn in various parts of the country, and have been given a second chance at plunging Japan into the vicious territorial Civil Wars of their own time. Some lords reawaken their failed ambitions to control the country, some pursue revenge on old enemies and recover lost loves, and some nobles just try to protect their homelands and peoples as guardian gods of the lands. Now, the Yami-Sengoku (Dark Civil Wars) are unfolding.

Kagetora has been reborn several times during the last 400 years as the powerful Reincarnate (Kanshosha), with psychic abilities and continuous memories, and with a special power to purify and exorcise unredeemed spirits.

However, his current reincarnation, Takaya, does not have his original memories, and represses his identity as Kagetora, for reasons which are initially unrevealed. Nevertheless, he's thrown into brutal psychic fights with reincarnated fighters and spirits of the land. Initially, he involves himself reluctantly because his beloved friend Yuzuru Narita is targeted. Soon, Takaya assumes the role of commander and fighter with boundless, sometimes destructive powers. Despite his outside aloofness and darkness, he cares for his men, his close friends and his younger sister, trying to carry on the lonely and thankless duty laid on him by Lord Uesugi Kenshin 400 years ago.

Uesugi Kagetora was a relatively obscure historical figure. He died young in an internal power struggle in the Uesugi family 400 years ago. He was a son adopted by Lord Uesugi Kenshin, initially as a hostage from the neighboring Houjou Clan, but was deeply respected and loved by Lord Kenshin.