Emperor Jimmu (Jinmu Tenno; given name: Kamuyamato Iwarebiko, born according to legend on January 1, 711 BCE, and died, again according to legend, on March 11, 585 BCE), was the mythical founder of Japan and is the first emperor named in the traditional lists of emperors. The Imperial house of Japan traditionally based its claim to the throne on its descent from Jimmu.
The name "Emperor Jimmu" is treated as the posthumous name of this mythical figure. In fact, being Chinese in form and Buddhist in implication, it must have been awarded centuries after the lifetime ascribed to him, as part of the compilation of legends about the origins of the Yamato dynasty known as the Kojiki. "Jimmu" literally means "divine might".
According to Shinto belief, Jimmu is regarded as a direct descendant of the sun goddess, Amaterasu. Amaterasu had a son called Ame no Oshihomimi no Mikoto and through him a grandson named Ninigi-no-Mikoto. She sent her grandson to the Japanese islands where he eventually married Princess Konohana-Sakuya. Among their three sons was Hikohohodemi no Mikoto, also called Yamasachi-hiko, who married Princess Toyotama. She was the daughter of Owatatsumi, the Japanese sea god and brother of Amaterasu. They had a single son called Hikonagisa Takeugaya Fukiaezu no Mikoto. The boy was abandoned by his parents at birth and consequently raised by Princess Tamayori, his mother's younger sister. They eventually married and had a total of four sons. The last of them became Emperor Jimmu.
In 1889, Kashihara Shrine was built to enshrine him in Kashihara, Nara.
New Year's Day in the Japanese lunisolar calendar was traditionally celebrated as the regnal day of Emperor Jimmu. In 1872, the Meiji government proclaimed that February 11, 660 BCE in the Gregorian calendar was the foundation day of Japan. This mythical date was commemorated in the holiday Kigensetsu ("Era Day") from 1872 to 1948, which was resurrected in 1966 as the holiday Kenkoku Kinen-bi ("National Foundation Day").