The Mysterious Forest is an unexplored forest on Vono Islands. At first it looks full of life, and appears to be the only place other than Lazulis Island where the land isn't dying. It's crowded with skeletons, Reptids, mystic plants and the huge Mystic Spider.
While exploring it, Mirania discovers that it is dying too, as she finds the Guardian's corpse. This renews her determination to find the cause of the land in the Empire dying.
Replaying[]
You can revisit the forest after Chapter 15. If you do return, it will have 5 gold chests. You can only bring 4 members of your team.
Also, if you head away from the gate at the start, you will find a group of Cave Cougars and Reptid Healers which guard 2 normal chests, one of which contains a Gnome Gold and the other a chance for a Guardian Blade.