Trivia: The name Yokai is never spoken in the film. Instead, he is referred to as "Guy in the Kabuki Mask", "Masked Man" or "Man in the Mask."
Trivia: In the original comics that serve as the basis for the film, Hiro is a child prodigy who fights to save his adoptive mother the Everwraith, an entity made from the souls of those killed in the atomic bomb attacks on Hiroshima and Nagasaki. Naturally, this was a little too edgy for Disney.
Answer: Because they are interfering with his plans and trying to stop him.
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