Moto Sekai Rank 1-i no Shoshinsha

Ray Endo discovers that completing a full-dive VR game named Prophecy Online can earn him money, and he dedicates himself to the game with the goal of becoming wealthy. After completing the game, he is informed that it will be shut down. Soon after, the real world faces a crisis as the same creatures from the game begin to threaten it. Ray, being the only one who has completed the game and understands its mechanics, sees this as a chance to use his knowledge and abilities for personal gain.