Tama River Headwaters was added to Your Favorites!
Chichibu-Tama-Kai NP, Yamanashi
Claim this place to tell your story your way.
At Mizuhi (水干, “stream’s end”), the Tama begins as a seep, vanishes underground, then reappears about 60 m downhill. From there, it travels 138 km via Okutama Lake to Tokyo Bay.
A small peak about 1 km from Mt. Kasatori divides 3 river basins: east-side rain joins the Arakawa, west-side rain feeds the Fuji River toward the Pacific, and south-side rain becomes the Tama, bound for Tokyo Bay.
A Kosuge farmer recalls that a villager brought home just 7 wasabi roots from Izu in the Meiji era. The newcomer grew larger and matured in 18 months, while the local, hotter type took 2 years.
In 1878, local hunter Narafuji Gorō guided Tokyo official Yamashiro Yūshi to Mizuhi during a source survey. Yamashiro’s report called it the place where the Tama’s true source emerges.
Near the source, local residents honor the water deity at the Mizuhi Festival. Its 21st edition was held at Kasatori Hut in 2026, with mountain-vegetable tempura, songs and dancing.
Kosuge’s spring-fed creeks stay around 12°C year-round, sustaining streamside wasabi beds. As growers age and cultivation declines, researchers at Tokyo University of Agriculture are conserving the village’s local strain.
Tokyo began managing the Tama’s source forests in 1901; by 2026 they covered 25,868 ha—the largest managed by a water utility in Japan. Old photos show Kasatori’s bare slopes, then young larch after planting.
