During the warmer months in Japan, you can find fireflies in numerous places across the country. From May 31st until June 4th, Shizuoka's Okawatakegasawa Park will host their 19th annual firefly viewing event where visitors can appreciate these fascinating creatures glowing and flickering against the night sky.
Admission to the event is priced at 200 yen, and it's scheduled to run from 7.30 pm until 9 pm each evening (last entry is at 8.25 pm). Do note that in the event of heavy rain the festival will be canceled, so check the forecast before you visit.