This is a story about a boy experiencing different worlds when he enters new place. Opening more doors, he finds people from different worlds. In spite of different appearances, they live in harmony and get along. The closed door in this book implies the walls which separate us from the people in unfamiliar worlds. But when we open those doors, we understand each other and live in harmony. Like my author's other work 'Pool', this book is a picture book with no text, leaving young readers to fill in the blank with their imagination.