※Below each holiday's significance is discussed. Each explanation starts with the corresponding part of Article II of the Law Regarding National Holidays which formally establishes it.
New Year's Day 元日
Article II: To celebrate the start of the year.
Colloquially also known as 元旦, New Year's Day commemorates the start of the new year (新年). This time period and the festival and customs associate with it are collectively known as 正月, which traditionally referred to the first month of the lunisolar calendar but has since been moved to the Western month of January ever since the solar Gregorian calendar was implemented in Japan as of 1872 AD. 正月 last four a three-day period known as 三が日.
元日 is also associated with the length of time known as 松の内 in which people have a decoration made of pine called 門松 outside their homes to welcome ancestral spirits back. Legend has it that one's ancestors become the kami of the fields and mountains and that on New Year's, they become 歳神（としがみ）, bringing them prosperity for the New Year. Rituals for the spirits are held with family by cleaning up the home and praying to a household shrine (神棚) meant for New Year's.
There are so many foods traditionally eaten during New Year celebration. These foods are referred to as お節料理. The biggest example of this is a seven-herb rice porridge known as 七草粥. Other foods that have become popularized to eat at this time include お雑煮, soup containing rice cakes and various vegetables, mochi (餅), and eating soba noodles on New Year's Eve (known as 年越し蕎麦).
The making of mochi is a common tradition at this time撞く. Steamed sticky rice (糯米) is put into wooden containers (臼) that is then patted with water by one person as another person hits （撞く）it with a large wooden mallet (杵). A mochi decoration for New Year's known as kagami mochi (鏡餅) is made by placing one round mochi cake atop another with a bitter orange (橙) placed on top.
At midnight, Buddhist temples ring their bells a total of 108 times, and the bell itself is known as (除夜の鐘), symbolizing getting rid of the 108 worldly temptations of everyone in the nation. There are various explanations as to why it is 108 rings, but it must be noted that there are temples which ring more than 108 times.
For the first day of the New Year, people go out and do things for the first time. One of the most important duties is one's first visit to the shrine (初詣), but if you sleep in and stay home all day, that's known as 寝正月.
New Year's is also when people send out postcards called 年賀状 to friends and relatives, but people refrain from sending postcards when a death has occurred in the family during the year. In this event, a family member sends out a mourning postcard known as 喪中葉書 to inform friends and relatives not to send a New Year's card out of respect to the one/those who have passed away in the family that year. This tradition is waning due to the influence of cellphones and the various social media apps that now exist.
When meeting people right before New Year's, people greet by saying よいお年を. Once the New Year has arrived, people then greet by saying あけましておめでとうございます. This is somewhat different than the English speaking world, which sums up both phrases with "Happy New Year."
Coming of Age Day 成人の日
Article II: To congratulate and encourage the youth for becoming self-aware of their adulthood and to live out their lives.
The age of maturity in Japanese culture is 20. Although the voting age has since been changed to 18 in recent years, 20 is still considered when one truly becomes an adult. On this day each year, the second Monday of January, coming-of-age ceremonies (成人式) are held by communities to congratulate and encourage those who have reached, or will reach, the age of 20 between April 2nd of the previous year and April 1st of the current year.
Such coming-of-age ceremonies have been celebrated in Japan since antiquity, and in the past, transitioning into adulthood also coincided with change in dress, which was called 元服. This ceremony was called 元服の儀, and in early modern times, it coincided with 小正月 (Little New Year), held on Jan. 15 which is usually in line with the first full moon of the New Year. In fact, Coming of Age Day was once always on Jan. 15 from the time it was officialized in 1948 AD until 2000 AD when its date was changed to the second Monday of January.
In modern society, due to Japan's low birth rate and subsequently shrinking percentage of young people, the number of attendees each year has been on a steady decline. Nonetheless, it still remains a federally recognized holiday.
National Foundation Day 建国記念の日
Article II: To remember the founding of the nation and foster a heart which loves the nation.
This holiday was established in 1966 AD and first held in 1967 AD as a day to reflect on the establishment of the nation to nurture love for the country (愛国心). From 1872 AD to 1948 AD, a similar holiday known as 紀元節 was held on the same day, which is the day which is believed to be when Emperor Jinmu acceded the throne in 660 BC. Although nothing spectacular is particularly held to commemorate this holiday, shrines and temples do hold festivals known as 建国祭 in honor of this day.
The Emperor's Birthday 天皇誕生日
Article II: To celebrate the Emperor's birthday.
The Emperor's Birthday celebrates the birthday of the reigning Emperor. When Emperor Naruhito ascended the throne in 2019 AD, this date moved accordingly to his birthday, which is on February 23rd. This tradition can be traced back to a similar festival from ancient China known as 天長節. This name was then inherited to refer to the birthdays of Japanese emperors. The name of the holiday was only changed to 天皇誕生日. During the reign of Emperor Akihito from 1989 AD to 2019 AD, this holiday was observed on December 23rd, but because he had abdicated the throne prior to his birthday, this holiday was subsequently not observed in 2019 AD. During the reign of Emperor Hirohito from 1926 AD to 1989 AD, this holiday was observed on Aril 29th.
Vernal Equinox Day 春分の日
Article II: To extol nature and to be compassionate to living things.
This public holiday commemorates the vernal equinox. Although the date is usually March 20th or March 21st, the exact date cannot be determined until the February of the previous year due to the necessity of astronomical calculations.
Like most modern holidays, it became an official holiday in 1948 AD in modern Japan. Prior to that year, the vernal equinox was honored in Shintoism with what is known as the 春季皇霊祭. However, due to its relation to 'State Shintoism,' this event in particular was subsequently abolished. Although honoring the dead of the imperial line may not be observed by the national public, this time is still meant to be when people go visit their loved one's graves, clean the gravestones (お墓掃除), and leave offerings of food or flowers.
Nowadays, it is part of a seven-day period known as 春の（お）彼岸. During this time, the daylight and night hours are of equal length, and it is also the beginning of spring according to the Japanese lunisolar calendar
. In speaking of the lunisolar calendar, it is also a time for farmers to pray for good luck for the upcoming season.
Shōwa Day 昭和の日
Article II: To look back over the Shōwa Era which underwent turbulent days and the achievement of restoration as well as to think about the country's future.
April 29th first started out as celebrating the birth of Emperor Hirohito (Emperor Shōwa), who passed away in 1989 AD. To commemorate his life and his era, it became a national holiday to reflect on the events of the Shōwa Era. However, from 1989 AD to 2007 AD, this holiday was actually known as Greenery Day (みどりの日).
Constitution Memorial Day 憲法記念日
Article II: To commemorate the execution of the Constitution of Japan and hope for the nation's growth.
May 3rd marks when the postwar constitution of modern Japan took effect. This day is meant to reflect the important of democracy in Japanese government. Each year, the National Diet building (国会議事堂) is open to the public for tourism.
Greenery Day みどりの日
Article II: To be intimate with nature while also giving thanks to its blessings and cultivate a relaxed mind.
This holiday was once the same as Shōwa Day, being held on April 29th. However, in 2007 AD, 'Greenery Day' was moved to May 4th, which up to that point had just been a 国民の休日 (citizen's holiday)--see below. Thus, one holiday became two holidays on separate dates. The purpose of this holiday practically involves insuring that each day of Golden Week is a holiday, but the symbolic nature of the holiday is to provide a day for people to enjoy the nature of Japan.
Children's Day こどもの日
Article II: To honor the character of children while also planning for their happiness as well as thanking their mothers.
This holiday was established in 1948 AD as a day to honor children and plan for their auspicious futures. It has its origin in the 端午の節句
. Traditionally, households with a male child will fly windsocks in the shape of a carp known as a 鯉幟 outside their home, and they may also decorate their homes with armor and/or samurai dolls. With the rebranding of this holiday, the Japanese government attempted to make this holiday include all children, but the emphasis on boys can still be felt.
Marine Day 海の日
Article II: To give thanks to the sea's bounty while hoping for the prosperity of Japan as a maritime nation.
First held in 1996 AD but established in 1995 AD, this holiday is celebrated on the third Monday to give citizens an opportunity to show their gratitude to the oceans and hoping for the continued prosperity of Japan. Because of its ideal timing in midsummer, many families take this holiday as an opportunity to go to the beach.
It was once known as Marine Memorial Day (海の記念日), which had been observed since 1941 AD to commemorate Emperor Meiji's voyage to Scotland in 1874 AD. Although it was initially held each year on July 20th since 1996 AD, it was changed to the third Monday of every July to coincide with the Happy Monday System legislation which took effect in 2003 AD.
Mountain Day 山の日
Article II: To gain the opportunity to be intimate with the mountains and give thanks to their bounties.
This holiday was first held in 2016 AD but established in 2014 AD as a day for citizens to appreciate Japan's mountains. This holiday incidentally coincides with vacation time intended for the Bon Festival (お盆) held in mid-August.
Respect for the Aged Day 敬老の日
Article II: To live and respect our elders who have devoted themselves to society over many years and celebrate their longevity.
Established in 1966 AD, on this day, people return home to visit and pay respect to their elders. The Japanese government has given out silver sake cups to those who reach the age of 100 (百歳のお祝いの銀杯), although in recent years the cups haven't been completely made of silver like they had been.
Autumnal Equinox Day 秋分の日
Article II: To revere one's ancestors and remember those who have passed.
This public holiday commemorates the autumnal equinox. Although the date is usually September 22nd or September 23rd, the exact date cannot be determined until the February of the previous year due to the necessity of astronomical calculations.
Like most modern holidays, it became an official holiday in 1948 AD in modern Japan. Prior to that year, the vernal equinox was honored in Shintoism with what is known as the 秋季皇霊祭. However, due to its relation to 'State Shintoism,' this event in particular was subsequently abolished. Although honoring the dead of the imperial line may not be observed by the national public, this time is still meant to be when people go visit their loved one's graves, clean the gravestones, and leave offerings of food or flowers.
Sports Day スポーツの日
Article II: While enjoying sports and cultivating a spirit of respecting others, to hope for the realization of a healthy and society full of vitality.
Established in 1966 AD under the name 体育の日 (~Health and Sports Day), this day is meant to cultivate a healthy mind and body. It was originally held on October 10th to commemorate the anniversary of the opening ceremony of the 1964 Tokyo Olympics, but it was subsequently changed to the second Monday of October in accordance with the Happy Monday System legislation. Ahead of the 2020 Tokyo Olympics, the name of the holiday became permanently changed to スポーツの日 as "sports" is far broader than "physical education." That same year, the holiday was moved to July 24th to coincide with the opening of the Olympics, but because the games were postponed due to COVID measures, Sports Day was observed instead on July 23rd, also irregular, to coincide with the opening ceremony.
Culture Day 文化の日
Article II: To love freedom and peace and promote culture.
This day is set aside to promote culture, the arts, and academics. It was established in 1948 AD. November 3rd up to that point coincided with a former national holiday known as 天長節, which honored the reign of Emperor Meiji as it was his birthday. Each year, this is when the emperor awards citizens the Order of Culture (文化勲章), which is an award given to those who have contributed greatly to Japan's art, literature, science, technology, etc.
Labor Thanksgiving Day 勤労感謝の日
Article II: To value labor, celebrate productivity, and for citizens to thank each other.
This national holiday was established in 1948 AD to honor everyone's labor and to give thanks to one another. Prior to this establishment, November 23rd had been associated with the imperial harvest festival known as 新嘗祭（にいなめさい）, which equates to the harvest of the Five Cereals (五穀)--the five farmed crops which were most important to society. These crops are generally understood in Japan as referring to soybeans (豆), wheat (麦), millet (黍), foxtail millet (粟), and rice (米).
One of the most famous events this day is the Nagano Ebisuko Fireworks Festival （長野えびす講煙火大会）. Schoolchildren will create cards to give out to police officers, firefighters, hospital workers, and other civil servants to show appreciation for their contributions to the nation. The meaning behind this day is very similar to thought process behind America's version of Thanksgiving.