The Mirror Window is a minimalist interior design located in Tokyo, Japan, designed by Kosaku Matsumoto. A partial renovation of the office area within a building complex that hosts a workshop space, an office, and a contemporary art gallery. The project was completed after designs and constructions made during three months of the architect’s on-site residency. The existing window with the dimensions of two by two and half meters – the first sight for visitors as they enter the space – had a barren view of an adjacent house. It was clear at first glance that changing this window would determine the nature of the new space. The idea was to abandon the use of this window would determine the nature of the new space.

The idea was to abandon the use of this window that had no view; instead, to reflect views of the interior space. The two-meter long plate of mirror was prepared after the dimensions of doma (an earth floor connecting the entrance and the outside), and installed behind the window along the span of the concrete fence.  The mirror reflects not only the interior space, but also adjacent walls and its neighborhood, revealing otherwise overlooked elements of the architecture from many different angles. It also created extra scope of sight and added a sense of depth to the space. The horizontal sliding windows were reused as the sliding doors inside. When the doors are open, doma becomes integral part of the indoor space. As a result, the renovation created additional views and open-air space through reworking the existing windows and exploring the reflective effects of mirror which intermingles the relationship between the interior and the exterior.