The Western system of counting years is commonly used in Japan, but the traditional Japanese system, based on the reigns of emperors, is still a part of everyday life. Since 1868, the accession of each new emperor has marked the beginning of a new era. The first year of a new era is numbered starting with one. In past eras, the name of the new era or 年号 (nengou) was selected by an emperor, but now the name selection process has its own committee. The name is chosen to be auspicious, and after an emperor dies he is known by that name.
The first year of each 皇紀 is called 元年 (gan nen) and the subsequent years are numbered 二年 (ni nen), 三年 (san nen), etc. Usually, the era ends when the emperor of that era dies, but in 2019 this tradition was broken and the emperor abdicated on April 30th. This was done for health reasons, and took a lot of red tape and preplanning to pull off this momentous change.
Many forms and documents in Japanese require your birthdate and other dates to be written in this form. Residence cards, driver’s licenses, and application forms use this format. It’s good to know your birth year, the current year in Reiwa (the current 皇紀), the start date of Reiwa, and the number and Western year of the last year of Heisei (the 皇紀 before the current one - 2019 was Heisei Year 31 before the first of May) if you will be filling out paperwork in Japan. Then you can easily fill out your own birthdate, and you can count from the last Heisei year/first Reiwa year if you need to know the date of a past event.
明治 Meiji (bright rule) 1868-1912
大正 Taishō (great righteousness) 1912-Dec 1926
昭和 Shōwa (shining peace) Dec 1926-Jan 7, 1989
平成 Heisei (peace growing) Jan 8, 1989-Apr 30, 2019
令和 Reiwa (beautiful harmony) May 1, 2019-Present
平成元年生まれです。
へいせい がんねん うまれです。
I was born in the first year of Heisei (1989).
平成17年生まれです。
へいせい 17ねん うまれです。
I was born in year 17 of Heisei (2005).
平成26年日本に留学しました。
へいせい 26ねん にほん に りゅうがくしました。
I studied abroad in Japan in Heisei year 26 (2014).
今日は令和2年10月1日です。
きょう は れいわ 2ねん 10がつ *ついたち です。
Today is October 1, Reiwa year 2 (2020).
(*Remember that the first 10 days of the month, the 14th, and the 24th have special counters.)