Tochigi is asteroid #19731 and also known as 1999 XA₁₅₁. Tochigi was discovered by the Lowell Observatory Near-Earth-Object Search (LONEOS) at the Anderson Mesa Station of the Lowell Observatory. Tochigi’s orbit is characterized by a semi-major axis of 3.19 Astronomical Units, an eccentricity of 0.10, a period of revolution of 2 082 days, and an inclination of 15.4 degrees.

Tochigi is named after Tochigi-ken (栃木県), the prefecture Tochigi in Japan. Tochigi Prefecture borders Fukushima Prefecture to the north, Gunma Prefecture to the west, Saitama Prefecture to the south, and Ibaraki Prefecture to the southeast. Utsunomiya is the capital and largest city of Tochigi Prefecture.

The prefecture seems to be named after the Japanese horse-chestnut (Aesculus turbinata). The name of this tree is tochi (栃) or tochi-no-ki (トチノキ / 栃の木) in Japanese.

Aesculus turbinata grows in gardens around the world, but naturally only in Japan. There it is used since ancient times. Today is the dessert tochimochi (栃餅) still made from Aesculus turbinata.

Tochigi hints to Japan and as a place name asteroid especially to a prefecture north of Tōkyō (東京). This is a by Japanese standards still rural area with Japanese horse-chestnut trees. Tochigi also hints to the Japanese horse-chestnut. For example together with Gunma would Tochigi also indicate vicinity because the two prefectures, which lend their names to the two place name asteroids, border each other. You can’t expect much more meanings than these from a place name asteroid.