Mt. Hiuchi, Mountain summit in Niigata Prefecture, Japan

Mt. Hiuchi is a 2,462 m summit on the border of Itoigawa and Myoko in Niigata Prefecture, the highest peak of the Kubiki Mountains. It lies between the active volcano Niigata-Yakeyama and the stratovolcano Mount Myoko, yet is not volcanic: sedimentary rock there has yielded fossils of marine animals. Its gentle east-west ridgeline carries a slightly lower western peak, Kage-Hiuchi.

Settlers entered the Sasagamine area at the southern foot with Takada domain permission in the late Edo period, and a pasture was established there in 1904. In 1917 Kaoru Tanaka's Japanese Alpine Club party traversed the Kubiki Three Mountains and reached the summit. The mountain joined Joshin'etsu Kogen National Park as a special protection zone on 10 July 1956, and in 2015 passed into Myoko-Togakushi Renzan National Park.

The mountain was chosen by poet Sumie Tanaka for her 100 Famous Flower Mountains of Japan, who named the Hakusankozakura (Primula cuneifolia var. hakusanensis) as its representative flower. In the Edo-period text Echigo Noshi the name is explained by the peak's resemblance to a flint stone (hiuchi). Two bronze eleven-faced Kannon hanging plaques, thought to be from the Kamakura period, were unearthed during replacement of the summit triangulation stone in the Showa 30s.

Climbers can reach the summit via multiple routes starting from Sasagemine, with overnight accommodation available at Koya mountain hut or Kurosawa-ike hut. The most suitable climbing season is during warmer months when trails are more accessible.

The summit area is a Siberian dwarf pine zone, and a spot on the south-southeast ridge called Raichō Plaza (Raichō-daira) is a Rock Ptarmigan habitat. The species is listed as Endangered Class I on Niigata Prefecture's Red List, and this mountain area marks the northern limit of its range in Japan.