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Yakushima NP, Kagoshima
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Sediment cores from Hananoego held wetland deposits beneath ash from the Kikai Caldera eruption about 7,300 years ago. Researchers say a marsh was already forming here before the eruption reshaped the landscape.
Just 4 mm long, a clam once thought unique to Yakushima got a 2026 identity twist: DNA and shell comparisons found the island’s “Habemameshijimi” is actually the widespread freshwater species Euglesa casertana.
A small shrine at Hananoego was built in 1844 by young men from Miyanoura. On their mountain pilgrimage, it is the final shrine stop in the highlands; offerings include salt, rice, shochu and a small amount of sea sand.
Hananoego is often called Japan’s southernmost high moor, but scientific surveys classify it as a low-to-intermediate mire: sphagnum moss dominates, yet its nearly level basin also receives surface water and groundwater.
Boardwalks help keep boots off the marsh, but structures there can also channel water and disrupt its natural spread. In 2025, managers removed 8 planks from a little-used section and planned to monitor how the area recovered.
Flow measurements show that water leaving Hananoego recedes more slowly than water flowing in from surrounding slopes—a sign that this little wetland stores rain and releases it gradually.
Before coastal roads linked Yakushima’s villages, paths from southern settlements met at Hananoego. It was a mountain crossroads as well as a sacred stopping place on routes toward the island’s high peaks.
