Emperor Kosho (孝昭天皇)
Emperor Kosho (506 B.C. - September 5, 393 B.C.) was the fifth emperor (reign: February 21, 475 B.C. - September 5, 393 B.C.), being described in "Kojiki" (The Records of Ancient Matters) and "Nihonshoki" (Chronicles of Japan). His Japanese-style posthumous name was Mimatsuhikokaeshine no Sumeramikoto, written as 観松彦香殖稲尊 or 御真津日子訶恵志泥命 (Kojiki). He was one of the so called Kesshi-Hachidai (Eight Undocumented Sovereigns), and it is commonly understood that he was a nonexistent Emperor (there is also the theory of his existence).
Imperial Palace
The capital was Wakigaminoike kokoro no miya.
(That is considered possibly to be present Ikenouchi, Gose City, Nara Prefecture.)
However, there is a description in kojiki that the capital was "Katsuragi no wakigami no miya."
Achievements
There is no particular description about his achievements. He was formally installed as Crown Prince on March 25, 489 B.C., then ascended the throne in 475 B.C. He died in the 83rd year of his reign. According to Nihonshoki, he died at the age of 114, while according to Kojiki, he died at the age of 93.
Misasagi (Imperial mausoleum)
Emperor Kosho was buried in Wakigami no hakata no yamanoe no misasagi. Currently, this misasagi is identified with a mountain-shaped barrow popularly known as "Hakata no yama," which is located in Mimuro, Gose City, Nara Prefecture.