Hyakume Child (百目の子)—usually just called Hyakume or Hyakume Boy (百目坊や)—is a character from the Akuma-kun franchise. He's best known as the sixth of Shingo Umoregi's Twelve Apostles in Saishinban Akuma-kun and its anime adaptation. He's the last of his kind, though nobody really knows why he survived when the rest of his race didn't.
He actually showed up way back in the 1968 GeGeGe no Kitarou series, though just in a quick cameo. In that first episode, he loses his baseball bat and Kitarou agrees to help him track it down.
Content compiled by AnimeList.moe from publicly available sources.