This small house in Tokyo sits on a tiny lot in a neighborhood of apartment buildings. Because of the small lot size, the only way to get sufficient living area was to build up, four stories tall. From the outside, the most distinguishing characteristic of the boxy house are the two glass facades which reveal a staircase winding around the perimeter of the home. On the inside, that staircase defines the character of the space. A tightly-wound staircase that zig-zagged back and forth over itself would have been more space-efficient. Instead, architect Hideaki Takayanagi opted for a stair that rises in a wide arc, sacrificing some space in favor of architectural interest.