She can be found in Tephra Cave only during the quest Stopping the Elopement in which she is involved, and can propose an unique trade there. After the Mechonis Core event, if she has not been migrated to Colony 6, she can be found underneath the Ether Plant in Eryth Sea, hidden away on the cliff at the westernmost edge from about 20:00 to 03:00. An easier way to find her is to go to the escape pod, and set the time to 18:00.