Tobias, Mary, and Sakuya set out to conquer the formidable labyrinth known as 'The One Sin', only to become lost within its intricate passages, inadvertently ensnaring their fellow guild members in the process. Amidst their struggle, a cryptic feline observer scrutinizes their missteps, leaving them to ponder whether this enigmatic presence belongs to a fellow player or an elusive non-player character.