Nibutani is asteroid #5135 and also known as 1990 UE. Nibutani was discovered by the Japanese astronomers Ueda Seiji (上田 清二) and Kaneda Hiroshi (金田 宏) at Kushiro-shi (釧路市), Kushiro-shichō (釧路支庁), Hokkaidō (北海道), Japan. Nibutani’s orbit is characterized by a semi-major axis of 2.24 Astronomical Units, an eccentricity of 0.13, a period of revolution of 1 224 days, and an inclination of 3.3 degrees.

Nibutani is named after a valley sacred to the indigenous Ainu people of Hokkaidō (北海道). The official naming citation states this and also that the name was suggested by a H. Ueda. Although several people exist with this name, none of them is an astronomer or an asteroid discoverer. H. Ueda seems to be a mix up of both of the names of the discoverers of the asteroid Nibutani, Ueda Seiji (上田 清二) and Kaneda Hiroshi (金田 宏). Also possible, but unlikely, is that who suggested the name is explicitly mentioned because it isn’t one of the discoverers and then also not an astronomer. The other possibility for mentioning the person could be that the other discoverer doesn’t support the name Nibutani because he never heard of it. Nibutani is barely recognizable by the description in the naming citation, so no part of the Wikipedia linked the articles on Nibutani (二風谷) and on the asteroid #5135 with each other; the Japanese part of the Wikipedia doesn’t know this asteroid.

Nibutani (二風谷) is a district in Biratori-chō (平取町) in Hidaka-shinkō-kyoku (日高振興局) in Hokkaidō (北海道). This island is also an area and a prefecture and divided into sub-prefectures. These host towns and cities. Nibutani (二風谷) is a district of a town. Eighty percent of the population there are Ainu, a proportion as large as nowhere else. Nibutani (二風谷) hosts two museums on history and culture of the Ainu.

Although Nibutani (二風谷) is written with kanji in Japanese, it still is only a phonetic writing. Nibutani (二風谷) transcribes the Ainu word Niptani (ニプタニ). So the kanji can’t be used to get a correct or additional meaning. Ainu is an isolated language and it is disputed to which language family it could belong. Ainu also is an almost extinct language with not more than fifteen remaining competent speakers, but Ainu – Japanese dictionaries exist, at least one of them. Niptani (ニプタニ) shall have the original meaning where trees grow in abundance. If this shouldn’t be correct, then it is impossible to find a translation for Nibutani and it would be an inexplicable place name.

Other asteroids already denote forests or groves, divide forests in sacred or only planned areas. So any such categorization doesn’t need to be done by Nibutani. Because Nibutani (二風谷) is a district of a town, so the trees growing in abundance could be a matter of the past or an impression, which only urbanized people get. Japanese cities are, much more than the cities in other countries, short in parks or green areas. Nibutani in any case is a place name asteroid hinting to the original territory of the Ainu. These indigenous people could be extinct in some years. I suggest that Nibutani hints to the threat of disappearing or becoming extinct.