Kibakichi (2005)

A man who can summon up his inner beast seeks to save others consigned to the same fate in this offbeat fusion of action and horror. Kibakichi is a Yokai, a strange shape-shifting creature who looks like a man but can transform himself into a beast at will and feeds on human flesh. When the leaders attempt to wipe out the Yokai, the survivors are forced to go underground, and Kibakichi wanders from town to town as a lone samurai. Kibakichi happens upon an outlaw town that hides a strange and deadly secret -- the evil Boss Ozino can turn humans into insects, and uses the bug people as slave labor, while the few surviving humans are kept as livestock to feed the humanoid insects. Unaware of this secret, Kibakichi throws in his lot with Ozino and his Mamoy clan, but when a renegade Mamoy takes control and exposes the ruse, Kibakichi allows his own monstrous alter ego to come forward and fight. ~ Mark Deming, Rovi