Hotaru (in English her name as Lumine) as a traveler from another world, came to Teyvat to explore more of the world and find her brother. Her background is unknown but when Yuna sees Hotaru, old memories come flooding back to her mind. Hotaru remembers everything and she knows herself as an influential simulacrum, elder and ascendant and is the first to be successfully created by his creator, making Hotaru feel that Yuna is her creator and does whatever it takes to achieve her goal.