Happy Monday System
The Happy Monday System refers to a set of modifications to Japanese law in 1998 and 2001 to move a number of public holidays in Japan to Mondays, creating three-day weekends for those with five-day work weeks. It is the Japanese equivalent of the 1969 Uniform Monday Holiday Act in the United States.
| Date | Moved to Monday | English name | Local name | Romanization |
| January 1 | New Year's Day | 元日 | Ganjitsu | |
| January 14 or January 15 | Coming of Age Day | 成人の日 | Seijin no hi | |
| February 11 | National Foundation Day | 建国記念の日 | Kenkoku kinen no hi | |
| February 23 | The Emperor's Birthday | 天皇誕生日 | Tennō tanjōbi | |
| March 20 or March 21 | Vernal Equinox Day | 春分の日 | Shunbun no hi | |
| April 29 | Shōwa Day | 昭和の日 | Shōwa no hi | |
| May 3 | Constitution Memorial Day | 憲法記念日 | Kenpō kinenbi | |
| May 4 | Greenery Day | みどりの日 | Midori no hi | |
| May 5 | Children's Day | 子供の日 | Kodomo no hi | |
| July 20 | Marine Day | 海の日 | Umi no hi | |
| August 11 | Mountain Day | 山の日 | Yama no hi | |
| September 15 | Respect for the Aged Day | 敬老の日 | Keirō no hi | |
| September 22 or September 23 | Autumnal Equinox Day | 秋分の日 | Shūbun no hi | |
| October 10 | Health and Sports Day | 体育の日 | Taiiku no hi | |
| November 3 | Culture Day | 文化の日 | Bunka no hi | |
| November 23 | Labor Thanksgiving Day | 勤労感謝の日 | Kinrō kansha no hi |