Seiya is a blonde-haired alien who visits Earth and takes a liking to Miyu, often disguising as Kanata to get close to her. He can read minds through a touch of the hand. He first appears in episode "The Mysterious Boy, Yaboshi Seiya" and after touching Miyu's hand had read her mind and wanted to take Ruu with him to planet Sharaku, his home planet to appear on a television program because people from planet Otto were rare, but after reading Miyu's hand, he understood that Ruu was precious to her and Kanata and stopped his pursuit of him. He has a sister, Rui, who saved him once from being sucked into a worm hole, and has had a sheltered childhood. His surname, Yaboshi, means night star.