The origin of National Foundation Day is New Year's Day in the traditional lunisolar calendar. On that day, the foundation of Japan by Emperor Jimmu was celebrated based on Nihonshoki, which states that Emperor Jimmu ascended to the throne on the first day of the first month.
In the Meiji period, the Japanese government designated the day as a national holiday. This coincided with the switch from the lunisolar calendar to the Gregorian calendar in 1873. In 1872, when the holiday was originally proclaimed,it was January 29 of the Gregorian calendar, which corresponded to Lunar New Year of 1873. Contrary to the government's expectation, this led people to see the day as just Lunar New Year, instead of National Foundation Day. In response, the government moved the holiday to February 11 of the Gregorian calendar in 1873. The government stated that it corresponded to Emperor Jimmu's regnal day but did not publish the exact method of computation.
In its original form, the holiday was named Empire Day . It is thought that the Meiji Emperor may have wanted to establish this holiday to bolster the legitimacy of the imperial family following the abolition of the Tokugawa Shogunate. The national holiday was supported by those who believed that focusing national attention on the emperor would serve a unifying purpose.Publicly linking his rule with the mythical first emperor, Jimmu, and thus Amaterasu, the Meiji Emperor declared himself the one, true ruler of Japan.
With large parades and festivals, in its time, Kigensetsu was considered one of the four major holidays of Japan.
Given its reliance on Shintoism and its reinforcement of the Japanese nobility, Kigensetsu was abolished following World War II. Ironically, February 11 was also the day when General MacArthur approved the draft version of the model Constitution in 1946.
The commemorative holiday was re-established as National Foundation Day in 1966. Though stripped of most of its overt references to the Emperor, National Foundation Day was still a day for expressing patriotism and love of the nation in the 1950s.
In contrast with the events associated with earlier Kigensetsu, celebrations for National Foundation Day are relatively muted. Customs include the raising of Japanese flags and reflection on the meaning of Japanese citizenship. The holiday is still relatively controversial however, and very overt expressions of nationalism or even patriotism are rare.