I, Raiden Shin, Was Awakened from a Century-long Slumber by Kamisato Ayaka

This book, also known as "Is Promoting Chinese Culture in the Genshin Impact World Wrong?" and "Ray Movie's Sister Complex Life," tells the story of a character who transmigrates into the Genshin Impact world, becoming Raiden Shin, but he's just a newbie who played the closed beta. Ayaka Kamisato: Are you the friend I've been waiting for? Raiden: Sister, is that you? [Yuan Yu]