February 11 is Kenkoku Kinenbi, or National Foundation Day, a national holiday in Japan. It is to remind them of there countries founders, and to show appreciation of their country.

In January 1873 Japan switched to the Gregorian calendar system, from the original Japanese Lunar Calendar. On this day the first Emperor of Japan was enthroned. Emperor Jinmu, the first Japanese Emperor. On this day it was also declared a national holiday, Kigensetsu.

Well by looking at the Nihon Shoki (The Chronicles of Japan) and comparing to the Japanese Lunar Calendar, February 11 was determined as the day of enthronement by calculating the date in the solar calendar corresponding to the date recorded in the Nihon Shoki.

Many Japanese believe that the enthroning of Emperor Jinmu, as described in the Nihon Shoki (The Chronicles of Japan), was not a historical fact but folklore. Before World War II government offices and schools throughout Japan held all sorts of celebrations on Kigensetsu, but after the war, the holiday was abolished for various reasons. Many people kept voicing that they wanted the return of the holiday. So much so they kept voicing themselves, until in 1966. In 1966 Kigen Setsu was again made a national holiday, but renamed Kenkoku Kinenbi, or National Foundation Day.