Picea koyamae (Koyama's spruce; Japanese: ヤツガタケトウヒ or やつがたくとうひ yatsugatake-tohhi) is a rare spruce, endemic to the Akaishi Mountains and Yatsugatake Mountains in central Honshu, Japan. It is an evergreen tree growing to 25 m (82 ft) tall, with a trunk diameter of up to a metre. It grows in small isolated stands in a limited area and the total area of occupation is less than 100 square kilometres (39 sq mi). Trees that are lost to typhoons are normally replaced with other faster-growing species and the International Union for Conservation of Nature has rated the tree as "critically endangered". Some trees are in cultivation as an ornamental tree.