Koji Kabuto is the main protagonist of Mazinger Z and the primary pilot of the eponymous robot, as well as a supporting protagonist in Great Mazinger and UFO Robot Grendizer.

Koji is famous for breaking the mold of main characters of his time, being hot-blooded and arrogant but learning sense as the series progressed.

Koji is a teenager of average height with an athletic build, black eyes, broad eyebrows, and black spiked hair that is combed back along with forward facing sideburns.

Koji and his brother, Shiro Kabuto, were raised by their grandfather after their parents were killed in a laboratory accident. After Juzo started to obsessively work on a secret project, a housekeeper named Rumi was hired to take care of them. By the time Koji got into high school, he spent most of his free time riding his motorcycle earning him a reputation as a skilled biker.