Mazinger Z
Kouji Kabuto is your typical high school student, except he's genuinely skilled at motorcycle riding. He lives with his younger brother Shiro and grandfather Juuzo, ever since his parents died in what was supposed to be an accident at his grandfather's lab.
Everything changes when Juuzo calls Kouji to meet him at a mountain cabin. The place explodes the moment Kouji arrives. Digging through the wreckage, he finds a hidden passage leading underground, where his grandfather is dying. With his last breath, Juuzo asks Kouji to pilot a robot called Mazinger Z and take down a man named Dr. Hell.
Kouji finds the massive humanoid robot waiting in the lab below, along with a hover pilder to control it. He honors his grandfather's final wish by joining Photon Power Labs and becoming Mazinger Z's pilot, launching a one-man war against Dr. Hell's forces.
Grendizer
Kouji serves as a supporting character and backup to the series' main protagonist, Duke Fleed, as they both fight the Vegan Empire. He starts out piloting the TFO, a lightly-armed reconnaissance mech with limited combat ability, before graduating to the Double Spazer—a jet-like machine that docks with Grendizer to give it flight and serious firepower, similar to how other support systems work.
Personality-wise, he hasn't changed much from the original series: stubborn, hotheaded, and always ready to throw a punch first. That said, he's grown more reasonable over time, willing to listen instead of charging blindly into every fight—though he's still usually the first one charging anyway.
Shin Mazinger
Kouji lives in a manor in Atami with his younger brother Shiro and grandfather Juuzo. Despite Juuzo being responsible for the accident that killed Kouji's parents, Kouji holds no grudge against him; he actually respects him deeply and will gladly fight anyone who talks trash about his grandfather.
When the Ashura Corps attacks Atami, Juuzo sends the hover pilder to Kouji and tells him to fly home with it. The manor gets completely destroyed the moment Kouji arrives—by design, since Juuzo's launching Mazinger Z from his underground lab. Once Kouji docks the pilder into Mazinger's head, his grandfather lays out the reality: with this robot, Kouji has the power to become anything—a god, a devil, whatever he wants. It's Juuzo's twisted way of atoning for killing his own son and daughter. Kouji accepts this overwhelming power, but makes his own choice: he'll use it to fight Dr. Hell and the Kabuto family's ancient enemy, along with all his mechanical beasts.
Content compiled by AnimeList.moe from publicly available sources.
