The day is decided at Cabinet meetings based on the booklet called " Calendar and Ephemeris "created by the National Astronomical Observatory of Japan and is announced in an official gazette as of the first weekday in February of the previous year.
国立天文台が作成する『暦象年表』という小冊子に基づいて閣議で決定され、前年2月第1平日付の官報で発表される。