Lumine

The Traveler is the protagonist and a playable character in Genshin Impact. At the beginning of the game, both genders are twin siblings from another world, traveling throughout the universe, until an Unknown God ambushed, capturing one of them, and sealed their ways to travel, leaving them stranded on Teyvat.
Whatever gender you choose, the name of the other sibling will be revealed. The male's name is Aether, while the female's is Lumine.
Lumine's names in other languages are Ying (Chinese: 荧 Yíng); Hotaru (Japanese: 蛍 Hotaru) which means "Firefly". While Aether's alternative names are Kong (Chinese: 空 Kōng); Sora (Japanese: 空 Sora) meaning "Sky"