Genshin Impact: Reincarnated as Hu Tao’s Younger Brother

Jiu Yue, a high school student from the 21st century, accidentally transmigrated to Teyvat and was taken in by Hu Tao's grandfather. He thought his life would simply pass by in peace and quiet, but gradually discovered that he seemed to be hiding some unspeakable secret.

(This story has both angst and sweetness, multiple female leads, Hu Tao as the main heroine, no System, a female-dominated world, and one protagonist with multiple supporting characters.)

(There will only be one transmigrator later on, so enjoy without worry.)