Ushio and Tora (2015)

While cleaning out some books from the store room, Ushio stumbles upon a door. Upon opening it, he finds a beast inside, which is stuck because of a spear holding it in place. The beast asks him to remove the spear, since only a human can do it. But since he says that he'll eat Ushio and wreck havoc among humans, Ushio doesn't help him. The beast's aura leaks, attracting many other yokais and Ushio is forced to free him to exterminate all the other yokais.