Manta Oyamada is an anxious, intelligent kid who basically lives with his nose in a dictionary—or encyclopedia, or whatever massive reference book he's carrying that day. He's got this weird sixth sense that lets him see ghosts and spirits, which is pretty unusual since he's not even a shaman. He's highly expressive and tends to panic easily, which makes sense given how often his unusually small stature has gotten him into genuinely dangerous situations. Most memorably, he once got mistaken for a nature spirit because of his height, and then actually got cut open and used as a bargaining chip during Faust VIII's match with You Asakura.
In the manga and anime, Manta basically serves as the narrator, walking viewers through the story and making sure everyone knows what's actually happening. He goes by "Morty" in the English dub (short for Mortimer). The creator Hiroyuki Takei has said he based Manta's character on the Japanese pop singer T.M.Revolution.
Content compiled by AnimeList.moe from publicly available sources.
