Three players venture into The World, an immersive online game, hoping to conquer one of its most notorious dungeons: The One Sin. What should be a straightforward raid becomes a nightmare when they get hopelessly lost in the labyrinth's twisting corridors, accidentally sealing other guild members inside with them. Now trapped and running low on supplies, the group scrambles to find an exit before the situation spirals into complete disaster. Watching from the shadows is a peculiar cat that shouldn't exist in this digital space. The creature moves with intentional purpose, almost sentient in ways that defy the game's normal mechanics. As paranoia sets in, the players begin questioning everything: Is this entity just another player? An NPC with hidden depths? Or something far more sinister lurking within The World itself? This three-episode OVA balances tense dungeon-crawling action with mounting psychological unease. It's built for people who enjoy watching groups unravel under pressure, where the real threat might come from within rather than without. The mysterious cat becomes the central enigma that drives everything forward.