Dr. Kabuto at some point began his scientific career in robotics and archaeology. In a mining expedition on Mt. Fuji, he discovered a new and rare element he dubbed Japanium. On another expedition in the Mediterranean island Bardos, Juzo and a group of scientist discovered the remains of an ancient empire and the Mechanical Beasts. One of the scientists who gives himself the title, Dr. Hell decided to weaponize the Mechanical Beasts in order to take over the world and had the other scientists killed. Dr. Kabuto was the only one to survive and started his own plans to create a robot that could defeat Dr. Hell. At some point he fathered a son named Kenzo who in turn became a scientist and fathered two sons of his own, Koji and Shiro. One day, Kenzo and his unnamed wife were killed in an accident. Juzo saved his son by turning him into a cyborg. To protect Kenzo's sons from psychological shock, Juzo took them under his care. However, with his work on the robot project, Juzo grew insane and estranged from his grandchildren with Koji taking the parental role.
Dr. Kabuto was an elderly man with aged white hair, a bald spot and a mustache. He has a hunched back and stands with legs far apart from each other.
Due to his extensive work on the Mazinger Z, Dr. Kabuto grew restless and insane. Compared to his more megalomaniacal counterpart from the original manga, Juzo is much more calm when speaking to Koji with his last breath. He also loves and trusts his family, making the Mazinger Z for Koji to use and taking care of him and Shiro when he could.
Dr. Kabuto was a brilliant scientist famed for finding Japanium and creating Super Alloy Z with it. Over the next several years, Prof. Kabuto would design and create giant robots to battle Dr. Hell. But only the Mazinger Z made it past production. Other robots included Minerva X and probably more, but were never seen or mentioned.
In the short time Dr. Kabuto had onscreen he had finally completed the Mazinger Z. However he is attacked by Dr. Hell's lieutenant Baron Ashura with an explosive. Koji hearing the explosion from his grandfather's lab rushes over. There he finds a dying Juzo and Koji tries to help. The doctor only tells him its useless to help him and explains to his grandson about Dr. Hell and about Mazinger Z. Juzo dies in Koji's arms and as Mechanical Beast rampages through the city, Koji grants his grandfather's wish to use the Mazinger to fight Dr. Hell. It is later revealed that Dr. Kabuto had other robots planned but never had time to finish them. One of the blueprints was stolen and was used to create Minerva X.
- In the early drafts, Juzo had a much different design that was later eventually used for the creation of Dr. Hell.