Mount Akaishi, Mountain peak in Minami Alps National Park, Japan

Mount Akaishi is a 3,120.5-meter peak on the border of Shizuoka and Nagano prefectures, the fourth-highest in the Akaishi Mountains. Its summit holds a first-order triangulation point, the highest such station in Japan, with a mountain hut just below to the south. The mountain body consists of green tuff and pyroclastic rocks, and the ridge above the timberline is covered with Siberian dwarf pine and alpine flower fields.

The first documented ascent took place in 1879 when Japanese Home Ministry officials reached the summit. This exploration helped map and document many of Japan's alpine peaks during that period.

The name refers to the red radiolarian chert of the massif, exposed along Akaishizawa, a headstream of the Ōi River on the south slope; it came into use after the Meiji era. The Akaishi Mountains take their name from this peak, recorded as "Akaishidake" in the 1820 Suruga-ki. Astronomer Makio Akiyama named asteroid (53157) Akaishidake after it in 1999.

Two main climbing routes serve the mountain with different difficulty levels and walking times. Be prepared for changing weather conditions and steep sections, particularly as you gain elevation through the climb.

The summit's first-order triangulation point, named "Akaishi-dake", is the highest such benchmark in Japan. The mountain also gave its name to asteroid (53157) Akaishidake, discovered by astronomer Makio Akiyama on 5 February 1999. The Akaishi Range itself takes its name from this peak, not the reverse.