Sunlight guided by mirrors on the roof hits the prism (approx. every half hour) and makes a rainbow-colored spectrum on the floor. The transparent tube that goes through the inside of the building right near the prism makes a tunnel for bees from the side of their honeycomb to the other side of flower garden.
The building is an abandoned silk-textile factory in Kiryu, which was famous in the past for its silk-textile manufacturing. The saw-tooth roof allows for only northern light to enter the building, and not the direct sunlight.