As said on one of the Rukiryaxe Posters, Rukiryo eats lightbulbs. This implies that it is a requirement along with the bag of sand, the light bulb and the can of worms for the Rukiryaxe quest, and on Halloween, the End Times Axe quest. It is not a light source or a logic structure, as it is not programmed to emit light.
It has a white, non-translucent surface. It builds a round shape at its end. Its box, however, is light-grey, emphasizing its decal on its front side.