It's not quite a Japanese summer without fireflies. Come see them at Setagaya's very own Firefly Festival that attracts a respectable 20,000 visitors every year. At the heart of the festival is the spectacle of approximately 3,000 fireflies released in a dome tent at the Setagaya Daikanyashiki parking lot. As dusk falls, watch these curious bugs illuminate the evening with their gentle glow.
The whole area will be celebrating summer with lanterns, food stalls and dance performances during the weekend as well. The market stalls between the car park of the Setagaya Daikanyashiki, the Kamimachi Tenso Shrine grounds and the car park of Setagaya Shinkin Bank will be open from 4pm and you'll be able to spot see fireflies from around 5pm.