A young wavemaster known only by the alias Tsukasa awakens in an MMORPG called The World, suffering from mild amnesia. He is unsure of his actions prior to waking up. Within The World, the Crimson Knights suspect him of hacking due to his association with a modified character resembling a cat. Trapped in the game, Tsukasa roams in search of answers, evading the knights and other players he encounters.
As he navigates The World, Tsukasa discovers a magical item shaped like a "guardian," which offers him protection against all dangers. Subaru, the commander of the Crimson Knights, together with other players who have come to know Tsukasa, embark on a quest to uncover the reason behind Tsukasa's inability to log out, aiming to solve the mystery before it escalates.
