This is also what led to his focus on reinventing natural materials. Traditional Japanese architecture is heavily focused upon rhythm and light, but using natural materials conventionally to achieve this limits your palette heavily. Instead, Kuma began taking materials like stone and using them as though they were light woods or glass, taking thin slices of it and using them as particles. His Stone Museum in Nasu (2000) is a great example of this, taking local stones to create soft and porous walls which shift in the light.