The Kugayama Firefly Festival (久我山ホタル祭り) is a charming, community-driven event held in early June along the banks of the Kanda River and the Tamagawa Josui. Now running for over 25 years, the festival centers on the release of approximately 2,000 to 3,000 fireflies (hotaru) into the local waterways. While the festivities officially begin at 1:00 PM with local shotengai vendors selling beer, yakitori, and sweets, the real draw occurs after sunset when the streetlights are dimmed to allow the soft, rhythmic glow of the fireflies to become visible.
For the best viewing experience, manage your expectations: this is a suburban matsuri rather than a dense forest display. The Tamagawa Josui River to the south of the station offers the darkest environment and the best chance for sightings, though the thick foliage requires a bit of patience to spot the intermittent flickers. The Kanda River path near the station is more accessible but tends to be brighter, which can make the fireflies harder to distinguish. Despite the crowds, the festival remains one of Tokyo’s most accessible nature events, located just 12 to 15 minutes from Shibuya via the Express or Rapid trains on the Keio Inokashira Line.
The festival atmosphere is most vibrant between 6:00 PM and 9:00 PM as the local shops set up outdoor seating, turning the residential streets into a lively open-air party. Because the fireflies are most active between 7:30 PM and 9:00 PM, it is recommended to enjoy the food stalls early before heading to the riverbanks as twilight fades. See here for suggestions on other places to enjoy the fireflies in and near Tokyo.
