One day, you wanders by chance into another world inhabited by giant creatures. Though you were supposed to be human-sized, you have become an existence no larger than the thumb of this world's inhabitants. Grass grows thick like a forest, butterflies are as large as birds of prey, and even frogs and mice are deadly. A single raindrop could blow you away, and there is no guarantee of survival if you spend a night outside. It was Tsubame who found you in such a world. He seems to be convinced that you is "Thumbelina"...?

Looking around, you find yourself in a room furnished with items your size. This is probably a dollhouse. Looking outside the house through the window, it was a world where everything was gigantic and terrifying to you. The man who called himself Tsubame was also a far larger existence.