Ainodake, Mountain summit in Southern Alps, Japan

Ainodake is a 3,190 m peak on the border of Yamanashi and Shizuoka prefectures, the second-highest in the Akaishi Mountains after Mount Kita and Japan's third-highest. Its upper slopes are bare rock with snow-filled gullies, while dense green vegetation covers the lower flanks. A cluster of red-roofed buildings sits low on the right side.

The mountain displays linear hollows formed by landslides near its peak, suggesting it may have been Japan's tallest mountain during the Last Glacial Maximum. These geological features tell the story of how the landscape changed over vast periods of time.

The name Ainodake means "the mountain in between", as it sits between Mount Kita and Mount Nōtori; the three are called Shiranesanzan. A rival theory held that Aino, not Nōtori, was the "bird mountain", because its snow-free dark ground looked like a small black bird. The summit lies on the Yamanashi–Shizuoka border, and its southern side is Shizuoka Prefecture's northernmost point.

There is no trail from the foot of the mountain to the summit, so Ainodake is usually climbed as part of a traverse of the Shiranesanzan or the wider Southern Alps. The main approach starts at Hirogawara toward Mount Kita or at Naraida Onsen toward Mount Notori. Huts such as Kitadake Sanso and Notori Koya stand on the saddles north and south of the peak, and a summer clinic operates for part of the season at Kitadake Sanso.

The summit marks the northernmost point of Shizuoka Prefecture, whose border with Yamanashi Prefecture runs across the peak. Landslides near the top created linear hollows, and some researchers estimate the mountain stood several dozen metres higher before those collapses.