Yoichi is the younger brother of the villain All For One, but is his opposite in nearly every way. Wishing to emulate the hero featured in his favorite comics book, Captain Hero, Yoichi always tries his best to be a good person, but still makes mistakes on occasion. Yoichi is shy and reserved, as he was sickly and not well socialized in his youth. He wants to seem confident and kindhearted, and will attempt to be a role model for others. He himself cannot fight evil, as he is physically weak.