Nihonsyoki is asteroid #5082 and also known as 1977 DN4. Kojiki is asteroid #5454 and also known as 1977 EW5. Both asteroids were discovered by the Japanese astronomers Kōsai Hiroki (香西 洋樹) and Furukawa Kiichirō (古川 麒一郎) at the Kiso Observatory. Kojiki is a member of the Hirayama-family Hygiea. Nihonsyoki is a member of the Hirayama-family Themis.

Kojiki and Nihonsyoki are named after Kojiki (古事記) and Nihonshoki (日本書紀), which are the earliest sources of Japanese history and also of Japanese mythology. Nihonshoki and Nihonsyoki are both correct transcriptions for Nihonshoki (日本書紀), only in different transcription systems. Nihonshoki (日本書紀) is more common. You can say that the asteroid Nihonsyoki got its name before the standardization. Possible are also the pronunciations Furukotofumi for the Kojiki (古事記) or Yamatobumi for the Nihonshoki (日本書紀), but these alternative pronunciations are barely used. The Kojiki (古事記) was compiled in 712 A.D., is mainly written in Classical Chinese, but contains also the first witnesses of the Japanese language. The Nihonshoki (日本書紀) was compiled in 720 A.D., is completely written in Classical Chinese and known as the historically more reliable book. This in turn made some religious movements declare the Kojiki (古事記) a holy scripture. Hence the naming citations call the Nihonshoki (日本書紀) the first source for Japanese history, but the Kojiki (古事記) a source for Japanese mythology. But in truth both are both. They don’t distinguish between history and mythology. This also holds true for the mythology of the ancient Greeks. Their mythology also begins with the creation of the world and slowly turns into history. If you follow history further back and further back, then you arrive at mythological tales. The Bible follows this same concept too, also beginning with the creation of the world, but documenting history in the later parts. This concept is a very common concept all around the world.

So Nihonshoki (日本書紀) and Kojiki (古事記) are together sources for Japanese mythology and they are together sources for early Japanese history. Western experts regard the written history of Japan as reliable beginning around 700 A.D. Everything before simply is declared to be mythology. Kojiki and Nihonsyoki are, as representatives of the master-texts of Japanese mythology, on the same level as Lohengrin or even more the level of Wagner or Homerus. Kojiki and Nihonsyoki are connections between the themes of Japanese mythology and some themes of Japanese history. Kojiki and Nihonsyoki can become relevant, when other asteroids of such themes are involved.