For some reason you are in a villa. Solve the mysteries and gimmicks in the room, get the key to the front door, and escape. If you cannot proceed, please use the hint function. The game is saved automatically, so you can continue playing even if you interrupt it. There is only one ending pattern.
I liked the TV drama I was watching during the production, and made that villa a room. If you watched the drama, it might be a familiar room.