Medusa and Kraken both mention they're working for Zande (they're actually the first you hear of him, which is nice and ominous). But I kind of appreciate the fact that one guy isn't behind all the world's problems for once; each city or region has at least one local villain who just can't get along with others, and in the course of vanquishing them, the Four Valiant Youths gain strength and connections that become vital to their cause by the end of the game.