Date and time notation in Japan
Date and time notation in Japan has historically followed the Japanese calendar and the nengō system of counting years. At the beginning of the Meiji period, Japan switched to the Gregorian calendar on Wednesday, 1 January 1873, but for many domestic and regional government paperwork, the Japanese year is retained. Japanese business and the people have also adopted various conventions in accordance with their use of kanji, the widespread use of passenger trains, and other aspects of daily life.
Date
The most commonly used date format in Japan is "year month day (weekday)", with the Japanese characters meaning "year", "month" and "day" inserted after the numerals. Example: 2008年12月31日 (水) for "Wednesday, December 31, 2008". The weekday is usually abbreviated to a single character, e.g. 水 for 水曜日 ("Wednesday"), but may also be written in full, then usually without surrounding parentheses. Apart from the Gregorian calendar, the Japanese Imperial calendar is also used, which bases the year on the current era, which in turn is based on the current emperor. The current era is 平成 Heisei and began in 1989. When using the Imperial calendar, the year is prefixed with the era. For example, the above date using the Imperial calendar is written as: 平成20年12月31日 (水); a more direct translation might be: Heisei year 20, Dec 31 (Wed).
Either form may be abbreviated as yy/mm/dd; periods as separators are not uncommon either. Examples: 20/12/31, 08.12.31. Ambiguities as to which calendar is used for the year are usually only resolved by the context in which the date appears, but Imperial calendar dates may be prefixed with a single character or letter denoting the era, e.g. 平20/12/31 or H20/12/31. This is a shorthand notation and full dates are often the preferred way of resolving such ambiguities.
time
In Japan is commenly used: 24-hour with all leading zeroes by the hour and all the leading zeroes by all the minutes + 12-hour without all leading zeroes by only the hour, by adding the "午前"(/"AM") [means "before noon"] or "午後"(/"PM") [means "after noon"] only before with following a space [午前 9:09(/AM 9:09) or 午後 9:09(/PM 9:09)], depending on wich part of the day it actually is at the moment in the open air in Japan.
