Horpina:
You'll find the Apherus Watchman hanging around in front of the prison where Apherus is chained. They've got the key to the prison, and probably several other interesting keys, but that's beside the point. Rumor has it that one of them just carries the key in a bundle on his back! Like that's safe! Meeoow! Though, I suppose there could be decoy bundles... and fake keys. Hmm. Ok, perhaps it's not as silly as it seemed at first.