A GaN layer is grown on a sapphire substrate, an SiO2 film is formed on the GaN layer, and a GaN semiconductor layer including an MQW active layer is then grown on the GaN layer and the SiO2 film using epitaxial lateral overgrowth. The kit includes items revealed to a child audience. Base station transmits the head slot by using the starting slot which located at predetermined position every mobile station on the TDMA radio channel, and transmits the continuous slots by using slots which follow the starting slot.