Oirase Stream (奥入瀬渓流, Oirase Keiryū) is a picturesque mountain stream in Aomori Prefecture that is one of Japan's most famous and popular autumn colors destinations. The stream flows along the floor of the Oirase Gorge, winding among trees which, while a lush green in spring and summer, turn brilliant shades of red, yellow and orange from late October through early November. Over a dozen waterfalls cascade down into the stream all along its length from the walls of the gorge.
Oirase Stream is the only outlet draining Lake Towada. It starts at Nenokuchi where there is a bus stop and a boat pier with connections to nearby Yasumiya Town. An easy-to-walk hiking trail leads along the most scenic, upper passage of the stream between Nenokuchi and Ishigedo, with many bridges, waterfalls and bus stops along the way. The trail is about 9 kilometers long and takes about 2.5 hours to walk one way.
Unfortunately for hikers, a busy road runs alongside the Oirase Stream, often crisscrossing the stream and hiking trail. This can be a distraction from the natural surroundings, although the traffic noise is somewhat overpowered by the rushing stream and absorbed into the forest. At the same time, the buses that travel on this route provide convenient transportation along the stream and an escape from bad weather.
Many cars and tour buses travel through here, and there is a good view of much of the stream from the road. It has become so congested in recent years, though, that it is now closed to cars on certain days during the peak tourist season in autumn. Free parking is available in Yasumiya and Yakeyama.