Tokine works as a secretary at TEN2, a mid-tier advertising agency where her days blend into routine paperwork and client management. That changes the moment she steps into the conference room to prepare for an important pitch. Light floods the space, the door seals shut, and she realizes she's trapped. Then Hacchin materializes, a small spirit-like creature with an impossible demand: solve the mystery hidden within this room or stay locked inside forever. What begins as panic transforms into something stranger. Hacchin presents clues scattered throughout the space, each one leading deeper into an enigma that shouldn't exist. Tokine finds herself genuinely invested in unraveling the puzzle, her corporate instincts giving way to curiosity. Each episode traps her in a new scenario, a fresh mystery to decode. The show balances playful puzzle-solving with genuine suspense, never quite letting you know if Tokine will actually escape or if something darker is happening behind Hacchin's cheerful facade.