He is the Guardian Character of Yuu Nikaidou and represents his dream of becoming a robot programmer. Everyone put him down,telling him building robots was pointless. Because of that, he doubted himself, flew into a rage and accidentally broke his egg before it hatched.
Years later, Amu restores it with her regenerating powers when she character transformed with Su, and Yuu is finally able to meet his Guardian Character. Soon after they met, this Guardian Character disappeared to be reborn again as a new character.
The Guardian Character has blue hair and green eyes. He wears glasses, a white scientist's coat, a blue shirt, green pants and brown shoes. His name is unknown.