Synopsis
Jiro Azuma is a young ninja raised by his grandfather who possesses the rare ability to communicate with animals. One day, he encounters a severely wounded mononoke named Rago. Mononoke are immortal demons with extraordinary supernatural powers. Moved by compassion, Jiro treats Rago's injuries. Soon afterward, another mononoke attacks, and Jiro sacrifices his life to protect Rago. To repay his kindness, Rago merges with Jiro and revives him. Although the fusion grants Jiro incredible demonic power, it also means he can never live as an ordinary human again.
After defeating the hostile mononoke, Jiro is captured by Ryosuke Shiba and Ichika Kishimojin, government-employed ninja from the Bureau of Espionage. The Bureau had been pursuing Rago ever since he escaped captivity with the help of a mysterious group of mononoke. Because of his irreversible bond with Rago, the Bureau no longer considers Jiro human, placing him under constant surveillance and effectively making him a prisoner.
Jiro eventually escapes to reunite with his grandfather, only to discover that the old man was once a member of the Bureau himself. After a heated confrontation, Jiro decides to return voluntarily, determined to fight both the mononoke threatening humanity and the people who seek to exploit his newfound abilities. On the journey back, he and Ichika are ambushed by mononoke hoping to seize Rago's power, but together they manage to defeat their attackers.
Soon, the Bureau forms a new special unit known as Black Torch. Led by Shiba, the squad consists of Jiro, Ichika, Hana, and a rookie ninja named Reiji. However, Reiji refuses to trust someone fused with a demon, leading to immediate tension and conflict between the two.
The team's first mission takes them to the site where Rago had once been sealed away. Although they successfully eliminate the mononoke guarding the area, the encounter leaves them with a cryptic message concerning Jiro's biological father.
Later, the squad undergoes specialized anti-mononoke training. Guided by the friendly mononoke Fuyo, each member faces a unique illusion designed to test their resolve. During the trial, Jiro and Rago confront a colossal black panther—the true form of Rago himself.
During another training session, Jiro and Rago witness a vision from the Edo period. There, they meet a mononoke named Amagi and discover that he was responsible for releasing Rago from his ancient prison.
Not long afterward, a series of mysterious murders is traced back to mononoke activity, prompting Black Torch to launch a new mission. Arriving in a haunted town, the squad quickly encounters the creatures responsible, leading to a fierce battle.
Jiro and Rago ultimately defeat Kanawa, but the victory comes with a shocking revelation. Rago realizes that by sharing his power with Jiro, he has unknowingly been draining Jiro's life force all along. Before he can reveal the truth, Amagi appears. Jiro attempts to fight but is effortlessly overwhelmed. Holding all the advantage, Amagi gives Rago an ultimatum: if he wishes to save Jiro's life, he must swear eternal loyalty to him.
With no better option, Rago allows Amagi to break the bond connecting him to Jiro. However, he outsmarts his enemy by leaving all of his power behind within Jiro before departing.
Afterward, Jiro struggles to control the overwhelming strength he inherited. His grandfather, Toshimasa, comes out of retirement and takes him to the Avidya Forest, where the forest's guardian, Ibuki, helps him master Rago's abilities. Following intense training, Ibuki reveals more about Amagi and his unique power to grow stronger by consuming other mononoke.
