Home/Saga/Saga City/Kase River Firefly Festival

Kase River Firefly Festival

firefliesbioluminescenceJunerivernature

Saga · Saga City

33.2880°N, 130.4100°E

The Kase River and its tributaries in the southern Saga mountains host one of Kyushu's most concentrated firefly populations — the combination of clean water, low agricultural chemical use, and dense riparian vegetation has maintained conditions for Genji-botaru (the large Japanese firefly) that have disappeared from most of Japan. The firefly season runs June 1–20, and the peak nights (June 8–12 in an average year) see thousands of simultaneous light signals over the river.

Essential Information

Opening Hours

June evenings only | From dusk (approximately 7:30 PM) | Peak viewing: 8:30–9:30 PM

Closed: Outside June 1–20 | Rain reduces firefly activity

Entrance Fee

Free

Best Season

June 1–20 | Peak: June 8–12 (average year) | Check local reports for exact peak

Visit Duration

1.5–2 hours (evening viewing)

Getting There

Access Information

Best viewing at the Kase River between Ogi City and Mitsuse Pass. Parking at Kase River Firefly Park, off Route 323. June evenings from dusk (approximately 19:30). Flashlight/phone light use should be minimized.

Insider Guide

Premium

**Peak timing:** Fireflies appear from 19:45 and reach maximum density around 20:30–21:30. The first 15 minutes after the first visible firefly are the most exciting — the emergence is rapid. **Photography:** Long exposure (30 seconds, f/2.8, ISO 800) captures the light trails without needing the fireflies to be stationary. Keep your position upwind of the river — the fireflies move toward their scent-based partners, and positioning accordingly improves density in frame.

View on Google Maps