Bacbakiri Ruins

You have to battle the last "form" of Sus (the leader of Kthibh), Red Sus, here. When you defeat them, Ynez appears, and congratulates you for defeating all the forms of Sus. But then, all the "forms" of Sus come back and turn back into Sus again. However, Ynez battles Sus for you, since you did enough things for them. Now, you can go to Vet Cave.