TsukuBlog Some Musings on the History of Japan`s National Foundation Day (Kenkoku Kinenbi, 建国記念日) 11 February, 2021
Before 1872 and the adoption of the Western Gregorian Calendar, the Japanese kept track of the passage of the years in one way – the NENGO system, in which a new ERA (年号) was proclaimed with the accession of each new emperor, with each successive year of rule during that reign numbered, advancing by one on each (Lunar) New Year`s Day (which usually fell in February). In fact, this system is STILL used in everyday Japanese life, with this year being the 3rd year REIWA (零和) – the name of the current NENGO – in addition to it being 2021.