Mc first encounters Lia on the island within the old castle/mansion(I don't remember) where he was sent as a mission in his competition with Ihelm to become the next decan of Imperial University. There Deculain' sences demonic scent that leads him to Carlos (hybrid of human and demon according to og plotline he was supposed to go mad and become a maniac) who became Lia's friend. Yuria uses MC's shock from seeing her(she looks very similar to how she looked irl) and teleports with her friends. Later when Deculain destroys castle to save stupid Ephirine he meets Ganesha with her students (Lia and her friends) MC says that will not hunt for Carlos unless he will appear before him himself. But MC thinks that Lia is just another eastern egg that was added to the game without his knowledge.
Later she appears when mc defends North, in past plotlines where Altar conquered the world (when Ephirine talks to fake g**), when she helps mc and emperor to translate text that Altar leader gave mc and in a few other instances.