Along the riverbank running near Kiri no Kōbō, the gently swaying, greenish-white lights have begun to glow once again, signaling the arrival of early summer. Flickering fleetingly from one moment to the next, these lights look just like stardust that has danced down onto the water’s edge. In this article, we would like to share the charm of the beautiful firefly watching around Kiri no Kōbō — an experience that will make you forget the busyness of everyday life.

Why This Place? A Firefly Habitat Nurtured by Rich Nature and Clear Streams

Fireflies are incredibly delicate creatures that cannot survive without clean water and a rich natural environment. The river flowing right next to Kiri no Kōbō remains largely untouched by human hands, preserving its lush trees and pristine, clear waters. This protected natural environment provides the perfect sanctuary for the fireflies, which is why it becomes a beautiful “Home of Fireflies” every year.

The Type of Firefly Found Here: Heike-hotaru (Heike Firefly)

The main species you can encounter along this riverbank is the “Heike-hotaru.” While they are slightly smaller than the larger Genji-hotaru, they are characterized by a gentler and somewhat more fleeting glow. There is an indescribable charm to the sight of their greenish-white lights blinking rapidly yet rhythmically, softly illuminating the river’s surface.

The Peak Season for the Most Abundant Displays

The best season to see the Heike-hotaru dancing most actively is usually from mid-June to early July. While it varies slightly depending on the local climate, the peak arrives right during the hot and humid periods between the rainy season spells. During these precious few weeks, they radiate the full brilliance of their short lives.

The Best Time Window: When Fireflies Become Active

Fireflies do not simply fly around all night long. The prime time to catch them is for about an hour between 20:00 and 21:00, once it has become completely dark. They fly around most actively during this window, and as the night deepens, they return to the bushes to rest.

Ideal Weather for Fireflies

If you are planning a firefly-watching trip, nights that meet the following conditions are ideal:

• Cloudy nights with little to no moonlight
• Days with almost no wind
• Hot and humid nights, such as after a rain shower

Conversely, on chilly nights, windy days, or during heavy rain, fireflies will hide behind leaves. Therefore, it is important to check the weather forecast before heading out.

Viewing Etiquette and Manners to Know Before You Go

Fireflies are extremely sensitive to strong light and environmental changes. To preserve this beautiful scenery for the future, please be sure to follow these manners:

• Strictly No Lights! Be Careful with Smartphone Screens, Flashlights, and Camera Flashes
  Fireflies communicate using their light. Exposure to strong artificial light prevents them from engaging in courtship behavior. Therefore, please absolutely refrain from looking at smartphone screens, shining flashlights onto the river, or using camera flashes. The rule of thumb is to keep any path-illuminating lights to an absolute minimum and turn them off entirely once you reach the riverbank.
• Watch Quietly: Do Not Catch Fireflies or Make Loud Noises
  Adult fireflies live for only about one to two weeks. Their lives are incredibly short. Please do not catch them to take home; instead, gently watch over them. Also, by keeping your voice down and listening closely, you can fully immerse yourself in a magical world woven by the murmuring of the river and the glowing fireflies.
• Watch Your Step: Proper Clothing and Items for a Safe Night Walk
  The riverbank is dark at night, and the footing can be poor in some areas. Avoid sandals and wear broken-in sneakers or walking shoes. Additionally, as there are many insects in the grassy areas, we recommend wearing long sleeves and long pants to minimize skin exposure.

The gentle lights of the Heike-hotaru, blinking here and there in the darkness, are a fleeting gift of early summer brought to us by rich nature.

Why not turn off the switch of your hectic daily routine for just a little while this summer, and spend a deeply soothing night by the riverbank near Kiri no Kōbō? As you listen to the soothing sound of the water, come and experience this healing moment woven by grains of light together with someone special.