Another construction feature is this room’s wall finish. It’s made of fine-grain sand mixed with a binder and painted over a mud wall, a fireproofing technique once common in traditional Japanese architecture. It not only helps to tame the heat and humidity of our seaside climate, but also works to soften the indoor light and diffuse it as it reflects off the tiny “mirrors” on the grains of sand. The sand finish around the round windows is actually the original material, scraped off the old wall and applied anew. A similar sand finish called juraku is visible on nearby surfaces.