The 1940 Summer Olympics and Tokyo Expo were planned as anniversary events, but were canceled due to the Second Sino-Japanese War. It was first used in the official calendar in 1873. For instance, 660 BC is counted as Kōki1. The Japanese imperial year ( 皇紀, kōki, or 紀元 kigen) is based on the date of the legendary founding of Japan by Emperor Jimmu in 660 BC. For the given name, see Kōki (given name).

Japanese Imperial Years ( kōki or kigen) Reiwa is the first era name whose characters come from a Japanese root source prior eras' names were taken from Chinese classic literature. The previous era, Heisei, came to an end on 30 April 2019, after Japan's former emperor, Akihito, abdicated the throne. The name of the new era was announced by the Japanese government on 1 April 2019, a month prior to Naruhito's succession to the throne. The present era, Reiwa, formally began on. It is also in general use in private and personal business. The nengō system remains in wide use, especially on official documents and government forms. Starting with Kōmei's grandson the Emperor Taishō in 1912, there has only been one gengō per emperor representing their entire reign. For instance, the Emperor Kōmei's reign (1846–1867) was split into seven eras, one of which lasted only one year. The reigning Emperor chooses the name associated with their regnal eras before 1868, multiple names were chosen throughout the same emperor's rule, such as to commemmorate a major event. The era name ( 元号, gengō) system (or, strictly speaking, gengō ( 元号)) was also introduced from China, and has been in continuous use since AD 701. However, its influence can still be felt in the idea of 'lucky and unlucky days' (described below), the traditional meanings behind the name of each month, and other features of modern Japanese calendars. In modern times, the old Chinese calendar is virtually ignored celebrations of the Lunar New Year are thus limited to Chinese and other Asian immigrant communities. Its sexagenary cycle was often used together with era names, as in the 1729 Ise calendar shown above, which is for 'the 14th year of Kyōhō, tsuchi-no-to no tori', i.e., 己酉. After that, Japan calculated its calendar using various Chinese calendar procedures, and from 1685, using Japanese variations of the Chinese procedures.

The lunisolar Chinese calendar was introduced to Japan via Korea in the middle of the sixth century. In the 21st century, however, the era system (gengo) and Western system (seireki) are the only ones still widely used. Over the centuries, Japan has used up to four systems for designating years: the Chinese sexagenary cycle, the era name ( 元号, gengō) system, the Japanese imperial year ( 皇紀, kōki, or 紀元 kigen) and the Western Common Era ( Anno Domini) ( 西暦, seireki ) system.

Lunar cycle october 2016