For a chance to see fireflies in all their glory, head to the countryside. It's a bit of a mouthful, but the Yuuyake Koyake Fureai no Sato complex is the perfect place to pitch up at dusk. Head to the lush, wooded area along the Kitaasa River and the little stream around the building for the best views.
There's also a campsite and hotel here if you want to make the night of it. You can even take a dip in the onsen.
The event takes place daily from 6pm to 8.45pm.