Medama-Oyaji

Medama-oyaji ( Japanese:目玉のおやじ, or 目玉親父, Lit. "Eyeball Father") is a Yo-kai who made an appearance in Yo-Kai Watch Shadowside:The Return of the Oni King. He is Kitarō's father. Once a fully-formed adult ghost, he perished of a disease, only to be reborn out of his decayed body as an anthropomorphic version of his own eyeball. He is an manga and anime character created by Shigeru Mizuki in 1960.

Biology
Medama-Oyaji appears has one giant eyeball for a head. He has a little body and wears no clothing. Before he was reborn around before Kitaro was born out of his mother, he was a full grown adult ghost that resembled a green-faced mummy.