Both a veritable ladies man and also somewhat mysterious, Aoyama becomes the 3rd pilot of Dai-Guard. Most of the time, Aoyama disappears after work. While his friends believe he's off womanizing, it turns out that Aoyama is caring for his sick mother. (Who personally doesn't want to become Aoyama's top priority over piloting Dai-Guard) As his experiences grow during the course of piloting Dai-Guard, he meets more people from his past that he once again crosses paths with. Like both his fellow pilots, he possesses personality traits that assist him in his role as Dai-Guard's engineer. He is always looking for ways to save time and effort, so not only does he regulate the robot's systems with clockwork proficiency, but he will intuitively notice methods by which the team can accomplish its goal with less effort.

Source: Wikipedia