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 much domestic and regional government paperwork, the Japanese year is retained. Japanese people and businesses 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
Time
Both the 12-hour and 24-hour notations are commonly used in Japan. The 24-hour notation is commonly used in Japan, especially in train schedules. The 12-hour notation is also commonly used, by adding 午前 or 午後 before the time, e.g. 午前10時 for 10 am. Japanese broadcasting and newspapers usually use a modified 12-hour notation in which midnight is 午前0時 and noon is 午後0時 and, for example, "quarter past midnight" is 午前0時15分. The AM/PM signs are also used, while the sign may be placed either before or after the time.Using the Japanese notation, times are written as "8時42分", with the characters for "hour" and "minute" added after the numerals. It is also common to simply write 8:42.
Times past midnight can also be counted past the 24 hour mark, usually when the associated activity spans across midnight. For example, bars or clubs may advertise as being open until "30時" . This is partly to avoid any ambiguity, partly because the closing time is considered part of the previous business day, and perhaps also due to cultural perceptions that the hours of darkness are counted as part of the previous day, rather than dividing the night between one day and the next. Television stations will also frequently use this notation in their late-night scheduling. This 30-hour clock form is rarely used in conversation.