How Japan's national holidays work: substitute holidays and citizens' holidays
Japan has sixteen national holidays fixed by law. This guide explains what happens when one falls on a Sunday, how a weekday squeezed between two holidays becomes a day off, which holidays are pinned to Mondays, and how the equinox dates are decided.
Holidays are set by law
Japan's holidays are defined in the Act on National Holidays (in force since 1948). The sixteen are New Year's Day, Coming of Age Day, National Foundation Day, the Emperor's Birthday, Vernal Equinox Day, Showa Day, Constitution Memorial Day, Greenery Day, Children's Day, Marine Day, Mountain Day, Respect for the Aged Day, Autumnal Equinox Day, Sports Day, Culture Day and Labour Thanksgiving Day.
They come in three kinds: fixed dates, holidays pinned to a Monday, and the two equinoxes, which are calculated astronomically. The Cabinet Office publishes the following year's list in the official gazette around February, and that is when the equinox dates become final. This site shows the published dates for years already announced and law-based calculations for later years.
Substitute holidays: when a holiday falls on a Sunday
If a national holiday falls on a Sunday, the nearest following day that is not itself a holiday becomes a day off. Usually that is the Monday, but when 3 May (Constitution Memorial Day) is a Sunday, 4 and 5 May are holidays too, so the substitute lands on 6 May.
There is no substitute for a holiday that falls on a Saturday. In such a year the country simply has one day off fewer.
Citizens' holidays: a weekday between two holidays
A weekday whose previous and next days are both national holidays becomes a holiday itself. For years this applied to 4 May; since Greenery Day moved to 4 May in 2007, it now appears in September, in years when Respect for the Aged Day and Autumnal Equinox Day sit one day apart (the so-called Silver Week).
About the official names
In the Cabinet Office's published list, both substitute holidays and citizens' holidays are recorded simply as 休日 (holiday). This site follows that convention and shows the common names only as a note.
Days off that are not national holidays
The year-end break (29 December to 3 January) is when government offices close, not a national holiday, and the mid-August Obon period is a customary break with no legal status. Because most companies close anyway, the travel and business cards on this site mention both periods.
Coming of Age Day, Marine Day, Respect for the Aged Day and Sports Day are pinned to Mondays and always produce a three-day weekend.