“All in all, you’re just another brick in the wall.” Pink Floyd’s rock opera The Wall—a protest hymn against education—comes to mind when looking at Tokyo’s Fuji Kindergarten. The Montessori preschool is so far removed from the traditional school system that its architect, Takaharu Tezuka, decided to completely do away with the object of Pink Floyd’s wrath: The building has no walls. Children aged two to six roam free in the ring-shaped building, where sliding doors open on to a central outside playground. Classrooms are separated by wooden boxes originally intended as shelves but often used for children’s play instead. It can get loud, but that’s part of the design: The children are meant to concentrate through the white noise of surrounding classes. Trees grow insi...