Ishikawa Seiji, a plain 31-year-old salaryman and a bachelor, has only one hobby: playing games. One day, he comes across the news of the death of the developer behind the worldwide hit RPG, “Fantasy Saga.” Shocked by the news, Seiji roams the internet and stumbles upon a message recruiting players for the new “Fantasy Saga” trial version. Without much thought, he clicks on the link and starts solving 100 challenging problems. Suddenly, he loses consciousness, and when he awakens, he finds himself in a sun-dappled forest. Reincarnated into the world of the game, Seiji is chased by slimes, attacked by bears, but gradually becomes stronger through these encounters. As he gets involved with others, he starts changing their lives as well. Will he be able to enjoy this new world to the fullest? Can he defeat the Demon Lord?