She hides in one of three areas. Mantis stays in a little cul-de-sac with a fresh water pond. If you put your back to the pond, (so you're facing the open field):
- Area 1 you're going to follow the cliff wall to the left until it hits the water. She is hidden next to a rock you'll find there.
- Area 2 you're going straight, across the field to the next valley, that has the large pink tree. She hides on the other side of that.
- Area 3 you're going straight toward's Velvet's tent, which is to the right. Go past it, then swim to the island a short distance across the water. She is hiding behind the tree there.