Koukichi Muta

A second-year student at the Kyoto Metropolitan Curse Technical College and a semi-grade 1 curse user. Known by the nickname "Ultimate Mechamaru," which is derived from the name of a robot in a robot anime that Koukichi once showed him. He is the owner of the "Heavenly Restriction," born without the flesh of his right arm and legs below the knees, and without sensation from the waist down. His skin is so fragile that even moonlight can burn it, and he constantly feels pain as if needles are being pricked all over his body. In exchange, he possesses a vast range of technique and powerful curse energy emission abilities across Japan. He is a practitioner of the puppet manipulation technique "Puppeteer Technique," and usually remotely controls a humanoid robot puppet "Ultimate Mechamaru" for combat and communication. This puppet is equipped with various weapons such as swords and cannons, capable of handling a wide range of situations from attack to defense. He can also operate multiple puppets simultaneously, overwhelming his opponents.

Initially, he was in a basement of a building, wrapped in bandages all over his body, but after obtaining a healthy body through Mahito's technique, he now wears the high school uniform and has a scar on his left cheek. His curse technique is not a power he wished for, and he has even stated that he would gladly exchange it for a healthy body if possible. Due to his appearance and physical condition, which prevent him from appearing in public, he has not been able to fully open up to those around him, and if he were to obtain a healthy body, he would like to meet his fellow sorcerers in person. Initially, despite not being human, he showed jealousy and irritation towards Panda, who could move freely under the sun, but after fighting at the exchange event, they became somewhat closer.

After obtaining a healthy body, his technique range has shrunk, but at the same time, he has charged the curse energy accumulated over the years he was bound to the body into the giant armored puppet "Ultimate Mechamaru Absolute Form Armored Puppet Ultimate Mechamaru Prototype Zero," allowing him to release a vast amount of special-grade curse energy temporarily.

In fact, he was an insider for the Fake Geto (Kasumi) group under the condition that Mahito would heal his body with "Idle Transfiguration" and not harm anyone from the Kyoto school. However, he resigned from being an insider when the cursed spirits attacked the people of the Kyoto school during the exchange event. Later, at a dam in a certain mountain, he fought Mahito and Fake Geto using the giant armored puppet after Mahito once changed his body to a healthy one due to their binding relationship, but he was defeated and died in the battle. However, before his death, he had arranged for a machine he created to activate if Gojo was sealed, which led to the cursed spirits' information being conveyed to Itadori and others. Additionally, he had arranged for his fellow Kyoto schoolmates, except for Todo, to be on a mission in a remote area away from Tokyo on the day of the Shibuya Incident.