"Mirage of Blaze: Rebels of the River Edge" is a supernatural action anime set in modern-day Japan, blending historical elements with paranormal intrigue. The story revolves around the conflict between two factions: the Uesugi forces, led by Naoe Nobutsuna, and the Takeda clan, represented by Kagetora Uesugi. Both factions are reincarnated warriors from the Sengoku period, bound by a curse that compels them to fight for control over powerful psychic entities known as "Possessors." These entities are the reincarnated souls of historical figures, capable of possessing living humans to achieve their goals.

Naoe Nobutsuna, a high-ranking Uesugi warrior, serves as the protector of Kagetora Uesugi, the reincarnation of the legendary Uesugi Kenshin. Naoe's loyalty is complicated by his unrequited love for Kagetora, who is initially unaware of their shared past. Kagetora, now living as a high school student named Takaya Ougi, struggles to reconcile his modern identity with his historical legacy. As the story progresses, Takaya begins to regain memories of his past life, awakening to his role as a leader in the ongoing battle against the Takeda clan.

The Takeda clan, led by Shingen Takeda and his loyal retainer, Haruie, seeks to harness the power of the Possessors to dominate the modern world. Their ambitions bring them into direct conflict with the Uesugi forces, leading to intense battles that blend historical warfare with supernatural abilities. The narrative explores themes of loyalty, identity, and the weight of history, as characters grapple with their dual lives and the consequences of their actions across centuries.

Key supporting characters include Ayako Kadowaki, a psychic medium who aids the Uesugi forces, and Chiaki Shuuhei, a former Takeda warrior who becomes an ally to Naoe and Takaya. The series delves into the complexities of their relationships, as well as the broader implications of the curse that binds them. The story is driven by a mix of political intrigue, personal drama, and supernatural conflict, culminating in a climactic struggle for control over the Possessors and the fate of both the past and present worlds.