Mazinger Z
Kouji Kabuto is the main character of the show, an ordinary student with exceptional skills in motorcycle riding. He lived with his brother Shiro and his grandfather Juuzo after his parents seemingly died in a lab accident caused by his grandfather.
One day, Kouji receives a call from his grandfather to meet him at his mountain cabin. Upon arrival, the cabin explodes. Searching through the debris, he discovers a hidden entrance into the mountain. Inside, he finds his dying grandfather who tells him to pilot "Mazinger Z" and stop Dr. Hell as his final wish.
Kouji proceeds into the hidden laboratory and discovers the large, humanoid robot Mazinger Z, along with the hover pilder used to control it. Honoring his grandfather's last wish, he joins forces with the Photon Power Labs and combats Dr. Hell's forces with Mazinger Z.
Grendizer
A supporting character, primarily serving as backup for Duke Fleed, the series' protagonist. He joins the war against the Vegan Empire alongside Duke Fleed and his allies. Initially, he pilots the TFO, a small reconnaissance unit with limited combat capability. Later on, he fights more directly with Duke using the Double Spazer, a jet-like machine with greater firepower that attaches itself to Grendizer, granting it flight capabilities similar to the Scrander.
His personality mirrors how he is portrayed in the original Mazinger Z anime. He is stubborn, hot-blooded, direct, and confrontational. However, he has matured somewhat, as seen in Great Mazinger. While still likely to be the first to charge into battle, he is now more open to reason.
Shin Mazinger
The protagonist of the series. Kouji lives with his younger brother Shiro and his grandfather Juuzo in their manor in Atami. Despite his grandfather causing the accident that apparently killed his parents, Kouji harbors no ill feelings towards him and holds him in high regard, even defending him against insults.
During the Ashura Corps' first attack on Atami, Juuzo sends out the hover pilder to Kouji, instructing him to use it to quickly fly home. As he reaches the manor, it is destroyed as Juuzo launches his life's work from his underground lab, the super robot Mazinger Z. After docking the pilder with Mazinger's head, Juuzo tells Kouji that with Mazinger, he has the power to do anything he wants with the world—he could even become a god or the devil. As ultimate penance for accidentally killing his parents, Juuzo will make his grandson superhuman. With this newfound power, Kouji decides to fight the Kabuto family's long-time enemy—Dr. Hell—and his army of mechanical beasts.
