Underground Empire (Temporarily)
|Family and Relations||Unknown|
|Voice Actor||Keiko Tomochika|
|First Appearance||Mazinger Z episode 20|
Mitsuo is an overweight boy around the late elementary school age. He wears a yellow collared shirt with an orange button on it, black circular glasses, shorts, and shoes.
Mitsuo is a weak willed and unconfident child who could not stand up to himself. Because of this, he had a hard time making friends and being taken seriously by others. Having been given power through Stronger gave him a superiority complex that made him believe no one could bother him again. However, after seeing Onimaru scared while in the cockpit, Mitsuo realized that he was just being a bully and decided to help Onimaru escape by working up the courage to jump to the Hover Pilder.
Mitsuo was bullied by Onimaru after coming to school and after Shiro saw that Mitsuo couldn't stand up for himself, refused to get friendly with him. Mitsuo saw the Stronger T4 and try to tell his classmates. But they all thought he was just trying to get attention since he was such a coward. This caused Onimaru and his goons to beat him up again.
He was later dragged away by a mysterious woman who offered him the chance to get back at everyone, especially Onimaru by piloting the Stronger T4. Mitsuo accepted and tricked Onimaru into getting in the cockpit with him. Mitsuo forced Onimaru to watch what he could do, but noticed that Onimaru became terrified. When Mitsuo stopped, the mysterious woman revealed herself to be Baron Ashura who was controlling the Mechanical Beast the whole time and revealed that Mitsuo and Onimaru were just his/her hostages. By the time Mazinger Z arrived, there were a few difficulties due to the hostages situation. With the boys still inside the Mechanical Beast, Koji rode up to them in the Hover Pilder. With Onimaru still scared, Mitsuo showed his courage which allowed Onimaru to join him. Afterwards, Mitsuo made peace with Onimaru.