There's an area in FF3J that's not listed in the walkthrough.

In the Salonia Catacombs, in the third basement (just before getting to the floor that has Odin), there's a 90 degree bend to the left from where you start. If you head right through a secret wall instead of left, you come across an area with 8 treasure chests (each has a monster inside), although not complete:

Chest: Ouroboros : Fenix Down
Chest: Ion : Elixer (i think)
Chest: Ion : Fenix Down
Chest: Ouroboros : Elixer
Chest: Ion : Fenix Down
Chest: Ouroboros : Elixer
Chest: Ion : Fenix Down
Chest: Ouroboros : Elixer

-unf