Rawan River

The Rawan River flows out of Lake Onneto through a primeval forest zone on the edge of Akan-Mashu National Park, carrying the lake's clear blue water toward the Tokachi River and on to the Pacific. The river is best known for its Rawan-buki, a giant variety of Japanese butterbur that grows two to three meters tall along the banks, a size found nowhere else in Japan. The plant has been designated Hokkaido Heritage. The reason for its unusual height here remains unexplained. The best time to see the Rawan-buki is between June and July, in the farmland surrounding the national park. Heavy harvesting has reduced wild colonies, so the plant is now also cultivated commercially as an Ashoro specialty.