The Ruby code
(Book)

"Bullied at school and home, Ash finds respite from his unhappy life in virtual reality games. One night, he spends his meager savings to help a stranger, who thanks him with a copy of an old fantasy game called The Glass Realm. While exploring the game, Ash meets a seemingly humble shopkeeper named Ruby. But from the start, Ruby seems different than the other townsfolk--especially when she and Ash stumble across an in-game quest designed not for the player, but for Ruby to solve. When Ruby begins developing powerful abilities that can rewrite the very code of the game, they realize she is far more than a pre-programmed side character."--,Publisher.