Oasahi-dake is the main peak on the Asahi Renpo (Alps) that straddles the borders of Niigata and Yamagata Prefectures. This is the most popular of the mountains along the Asahi Renpo. Also, people often use as Oasahi-dake a starting or ending point of traverses of the Asahi Renpo.

Not only Oasahi-dake, but a lot of the Asahi Renpo are pristine. They are truly as nature intended. As such, it is recommended for mountain climbers to walk all the way from the trailhead to the summit on their own two feet. To do so, sufficient food and supplies are necessary to climb what is a long and technically-demanding peak.

In the Age of Provincial Wars, Naoe Kanetsugu, a vassal of the Uesugi family, started governing the Yonezawa and Shonai domains. However, in order to reach the Shonai area, he had to travel through enemy land ruled by the Mogami family. Naoe devised a way to fulfil his duty by secretly constructing a road over the Asahi Mountain Range from Yonezawa. Parts of the zigzag road still remain today on the mountainside of Ito-dake.

The Asahi Renpo (Asahi Alps)

The mountains on the Asahi Renpo also on the 100 Famous Mountains of Yamagata are (from north to south) Shojiga-take, Ito-dake, Tengusumotori-yama, Torihara-yama, Koasahi-dake, Osasahi-dake, and Okitama Ha-yama.

Higure-sawa Trail (8 hours one-way)

The Higure-sawa Trail up Oasahi-dake starts in Nishikawa Town. There are two trails that begin at the Higure-sawa emergency hut at the end of the road. The first goes via Kodera-yama and Koasahi-dake, and the second via Tatsumon-yama and Nishiasahi-dake. For the trail that goes via Tatsumon-yama, a little bit below the Tatsumon-yama junction, there is an emergency hut with a water supply and toilets.

Getting there: The access road there is only partially sealed. The unsealed section is for the most part fine, but near the Higure-sawa hut there a parts that are difficult to get by after rainfall, so take due care. There are about 10 car parks and toilets at the Higure-sawa Hut.

Kodera Kosen Trail (6 hours one-way)

The Kodera Kosen Trail up Oasahi-dake starts in Oe Town. Leaving from the end of the road at Kodera Kosen (accommodation available), there are two available trails; the first trail goes via Kodera-yama and Koasahi-dake, and the second goes via Torihara-yama and Koasahi-dake. Many opt to take the trail that goes via Kodera-yama as it is relatively easy. Experienced climbers have been known to go to the top and back in one day. Most choose to stay in the emergency hut at the summit of Oasahi-dake.

Asahi Kosen (Nakatsuru-one Ridge) Trail (6 hours one-way)

The Asahi Kosen Trail up Oasahi-dake starts in Asahi Town. Leaving from the end of the road at Asahi Kosen (accommodation available), there are three available trails; the trail that goes up the Nakatsuru-one Ridge straight to the summit of Oasahi-dake, the trail that goes via Torihara-yama and Koasahi-dake, and the trail that goes via Mikagemori-yama. Of these, the trail that goes via Torihara-yama has an emergency hut with a water supply and toilets. In summer, there is a bus to Asahi Kosen for mountain climbers (Japanese).

References

Asahi Kosen Naturalist House

Oe-machi Tourism Website