“The idea with the Toshima City Office was to softly divide the interior and exterior using what we named ‘Eco Veil’,” Kuma tells Quartz. “This concept groups four kinds of panels, each with its own function.” Solar panels, recycled wood, window blinds and spaces for plants are used equally to layer the exterior. “The panels work like leaves do for trees,” Kuma said. “For this building, we adapted the Japanese concept of the ‘gentle divide’ to the modern context.”