Long ago, demon-like creatures known as Oni butchered humans and brought on destruction solely for their own delight. A lone man named Momotarou opposed these gruesome, near-invincible monsters, but the war against them was just beginning. Thousands of years in the future, temperamental gun enthusiast Shiki Ichinose leads a carefree life. However, after his expulsion from school, everything changes. Shiki is suddenly attacked by a man and is rescued by his adoptive father, Tsuyoshi. As the two flee, Tsuyoshi reveals that Shiki is actually a descendant of the Oni, while both he and their pursuer are from the Momotarou lineage. The two Momotarou soon clash in a fierce battle, and Tsuyoshi sacrifices himself to protect Shiki. Devastated, Shiki awakens to his Oni blood that grants him immense strength at the cost of going berserk. Although the enemy escapes, Naito Mudano, an Oni teacher at Rasetsu Academy, takes an interest in Shiki. Under Mudano's guidance, Shiki must learn to control the Oni blood—if he ever hopes to avenge his father.

It is the Edo period. Ichitarou, the young master of Nagasakiya, one of the largest stores in Nihonbashi, has been in poor health since birth and is unable to go out. However, Ichitarou is always protected by demons such as Shirasawa and Inugami, who serve him. One night, Ichitarou goes out secretly and witnesses a murder. From that day on, bizarre murders begin to occur one after another in Edo... With the help of the demons, Ichitarou's search for the culprit begins!

Based on "Unico and the Kingdom of the Sun," which was newly written as a theater version, this animated film features a battle between the wizard Kukuruku and Unico. Kukuruku builds a castle using dolls transformed from men as building parts. The story revolves around the sorrow and terror of men who have been transfigured into dolls, and a girl named Cherry who wishes to recover the kindness in her brother, who is a student of Kukuruku. This work reminds us of the fact that "transformation" or "transfiguration" - favorite themes of Tezuka Osamu - involves not only material aspects, but also man's immaterial heart.