It is now a fantasy in the past that a stream is brightly decorated with fireflies flying in the twilight early in the summer. However, here, on the Gion River, Ogi City, Saga Pref., hundreds of thousands of fireflies fly around to create a fantastic illumination show from the end of May to the early June every year. In the mountains around Mt. Tenzan with an altitude of 1046 meters, there spring out a lot of small streams and those streams run into the Gion River, which is the main Stream of the Kiyomizu River, one of Japan’s 100 Fine Water. The fireflies are the fruit of hard-working efforts made by the people in Ogi town to live in harmony with nature. They were selected as one of the nationally protected wildlife.