Oirase Stream — A Primeval Paradise of Moss and Crystal Waters

Flowing northeast from Lake Towada through a virgin forest gorge, the Oirase Stream (Oirase Keiryu) is one of Japan's most celebrated natural walks — 14 kilometers of crystal-clear mountain water tumbling over mossy boulders, beneath a cathedral canopy of maple, oak, and beech trees. Unlike most scenic walks that offer occasional views, Oirase immerses you continuously: every step brings a new waterfall, a new cascade of white water, or a new composition of green light filtering through ancient leaves.

Highlights

The stream's most celebrated stretch runs from Yakeyama to Nenokuchi at Lake Towada's eastern shore. Along this route, fourteen named waterfalls drop into the stream — Choshi Otaki, the largest at 7 meters, thunders through mossy walls of dark basalt. Smaller falls cascade from every cliff face, and side channels branch into the forest creating a multi-layered, constantly moving water world.

The mosses are extraordinary: dozens of species coat every boulder, root, and fallen tree in shades ranging from bright emerald to deep forest green, giving the gorge a lush, otherworldly texture. In autumn, the deciduous canopy explodes in gold and crimson, reflecting in the stream and creating one of Japan's most celebrated autumn foliage scenes.

The stream is protected as part of Towada-Hachimantai National Park. A paved path and in some sections a road run alongside the stream — cycling is permitted (rental available) and many visitors walk the full 14 kilometers one-way.

Getting There & Tips

Access from Aomori or Towada-Minami by bus to Nenokuchi or Yakeyama. Seasonal shuttle buses run along the stream road. Walking from Yakeyama to Nenokuchi (about 4 hours) is the classic approach — slightly downhill, ending at the lake.

Best Time to Visit

October is peak autumn foliage — the most famous season. Summer (June–August) offers lush green beauty without crowds. Spring brings fresh growth and snowmelt water volume.