【Japanese Culture】What is April 6th? Summary of the Origin and Events of "Castle Day"

Himeji Castle in spring cherry blossoms

Highly stacked stone walls and overlapping tile roofs - Japanese castles remain in various regions as remnants of the time when samurais ruled Japan. Not only those built at the time of construction, but also those where only the stone walls retain the appearance of the time, and even those rebuilt in modern times are scattered throughout Japan. If you have ever toured Japan, there are certainly not a few people who have visited the local area. This time, we will introduce a memorial day related to Japanese castles.

The origin of the establishment of Castle Memorial Day on April 6

Himeji Castle in autumn

How is the anniversary of this castle determined? In Japan, this anniversary, known as "Castle Day" (城の日 / shiro no hi) is set for April 6th. This anniversary was established in 1974 by the Japan Castle Association, a public interest incorporated foundation. In addition to this, Himeji City, where the "Himeji Castle" we will introduce later is located, designated April 6th as "Castle Day" in 1990.

This seems to be derived from the fact that the numbers 4 and 6 can be read as "shi ro" in Goroawase (mnemonic sounds or wordplay), and on this day, the admission fee for the facility was free. However, due to the increase in the number of visitors, this event ended in 2007. Instead, a system was started to make the admission fee free on "December 11th, the day Himeji Castle was registered as a World Heritage Site".

A female tourist and Osaka Castle

By the way, let's reaffirm why we can read the numbers 4 and 6, which make up April 6th, as "shiro", which is derived from these numbers. In Japan, there is a rule (wordplay) called "Goroawase", where we assign sounds that become the readings of each number from 1 to 9, as well as 10 and 100, and enjoy the combination of a (Japanese) word and the sequence of numbers assigned to the sounds that make up that word.

In the case of "shiro" this time, the number 4 has sounds like "yo", "yon", "shi", and the number 6 has sounds like "ro", "roku", "mu". From these, we can take the "shi" of 4 and the "ro" of 6 to read as "shiro", and it is possible to associate the Japanese word "castle (shiro)" that has this sound with the date consisting of the two numbers 4 and 6, April 6th.

Information on "Castle Day" related events

Fireworks and Osaka Castle

Although April 6th is "Castle Day", we were unable to confirm any events specifically related to this day at the moment. However, various "Castle Festivals" are held at castles all over Japan on different dates, so we will provide information about these events.

National Treasure Matsue Castle Castle Festival (Shimane Prefecture): March 27 - April 10, 2024

National Treasure Matsue Castle
Matsue Warrior Parade

The "National Treasure Matsue Castle Castle Festival" will be held in Matsue Castle Park in Shimane Prefecture. During the period, the opening of the Castle Mountain Honmaru Square and the lighting up of the cherry trees are planned. In relation to this, the "17th Horio Yoshiharu Matsue Samurai Parade" will be held on April 6th. Coincidentally, this year it overlaps with the previously introduced "Castle Day". In this event, a samurai parade of about 170 people, including horse-riding warriors, will march through the city towards Matsue Castle. In this parade, performances by the gun squad and each team are also planned, making it a major highlight.

390th Inuyama Festival (Aichi Prefecture): April 6th and 7th, 2024

Inuyama Festival
Inuyama Festival

This festival is the "Festival of Haritsuna Shrine" located at the foot of Inuyama Castle, featuring floats with mechanical dolls and lantern-lit floats parading at night. It is also known for being registered as a "UNESCO Intangible Cultural Heritage" in 2016.

Hikone Castle Cherry Blossom Festival (Shiga Prefecture): March 28 - April 16, 2024

Photo provided by: Biwako Visitors Bureau
Photo provided by: Biwako Visitors Bureau

At the Hikone Castle area, the "Hikone Castle Cherry Blossom Festival" is held, where the "Cherry Blossom Light Up along the Moat" takes place. Visitors gather for cherry blossom viewing, aiming for about 1,100 cherry trees centered around Hikone Castle.

Himeji Castle Festival (Hyogo Prefecture): May 17-19, 2024

Himeji Castle
Provided by: Himeji City
Castle Festival (Historical Parade)
Provided by: Himeji City

The "Himeji Castle Festival" will be held from May 17th to 19th at Otemae Park and Otemae Street around Himeji Castle. The highlight is the Himeji Daimyo Procession. The grand parade of samurai, daimyo, and princesses is a sight to behold.

Five National Treasure Castles in Japan to Learn About in Relation to "Castle Day"

It is known that there are currently 12 castle towers remaining in Japan, five of which are designated as national treasures. At FUN! JAPAN, we have compiled articles about each of these five castles counted as "National Treasure Five Castles". Let's take a look back at each of them here.

Himeji Castle

Himeji Castle
Provided by: Himeji City

Himeji Castle is a castle located in Himeji City, Hyogo Prefecture. It is known as the only castle among the five national treasure castles that is registered as a World Heritage Site. The beautiful landscape of its white walls is likened to the figure of a white heron spreading its wings, and it is also affectionately called "White Heron Castle" (Hakuro-jou). The current Himeji Castle was built in 1609 by the fourth lord, Terumasa Ikeda, and miraculously survived the Himeji air raid in 1945, leading up to the present day. In recent years, major renovation work has been completed, and its beautiful white appearance continues to fascinate many castle fans.

Matsue Castle

Matsue Castle

Matsue Castle is a castle located in Matsue City, Shimane Prefecture. When viewed from the front, the triangular part of the castle looks like spread wings, hence it is also called "Plover Castle" (Chidori-jou). It is a historic castle built by the warlord Horio Yoshiharu in 1600 and was designated as a national treasure in 2015. From the top floor of the castle tower, you can have a 360-degree view of the surroundings, including Lake Shinji and Yomegashima. Also, you can tour the moat surrounding the castle by riding a roofed boat.

Hikone Castle

Photo provided by: Biwako Visitors Bureau

Hikone Castle is a castle located in Hikone City, Shiga Prefecture. It is also known as "Golden Tortoise Castle" (Konki-jou) because it was built on Hikone Mountain, which has the nickname "Konkisan" (literal transalation: Mt. Golden Tortoise). The castle was built between 1604 and 1622, and from the top of the castle, you can enjoy a 360-degree panorama of Hikone city and Lake Biwa, the largest lake in Japan. In spring, beautiful cherry blossoms in full bloom line up along the moat, and you can also tour the inside of the castle from the water by boat.

Matsumoto Castle

Matsumoto Castle

Photo provided by: Matsumoto Castle Management Division

Matsumoto Castle is a castle located in Matsumoto City, Nagano Prefecture. This jet-black castle is symbolized by its five-tiered castle, which was built by Ishikawa Kazumasa and his son, Ishikawa Yasunaga, who were the castle lords from 1590 to 1613. The outer walls are painted with white plaster and black lacquer, a symbolic color applied to resemble the appearance of Osaka Castle, which was owned by the then-powerful Toyotomi Hideyoshi. The black lacquer coating protected the castle from rain and also served to repel rainwater.

Inuyama Castle

Inuyama Castle

Inuyama Castle is a castle located in Inuyama City, Aichi Prefecture. It was built in 1537 and is also known as "Hakutei Castle". The only existing structure is the watchtower-style keep, but from the castle, you can overlook the Kiso River, which forms the border between Aichi and Gifu Prefectures. Also, Inuyama Castle was a national treasure and was privately owned for a long time, but the current owner is the Inuyama Castle Hakutei Bunko.

In Conclusion: Exploring Castles with "Castle Stamps"

Female tourist and Osaka Castle

In Japan, for several years now, there has been a trend of collecting 'Goshuin', which are stamps or inscriptions given at shrines and temples when you visit, in a booklet called a 'Goshuincho'. This is considered a 'record of your connection with the gods and Buddhas as proof of your visit', and consists of 'a seal, and ink writing of the name of the shrine or temple, and the name of the god or Buddha'.

On the other hand, separate from this, there are places known as tourist destinations, such as castles, that issue something called 'Castle Stamps' (gojouin). This can be described as a 'certificate or souvenir of your visit to the castle', and typically consists of 'ink writing (calligraphy) of the castle name on Japanese paper, and a red seal of the castle lord's family crest'.

According to one theory, 'as of 2020, more than 500 castles are issuing them', so if you are interested in Japanese castle architecture, or if you are thinking of starting a 'castle tour', why not try visiting various castles with your own 'Castle Stamp Book' in hand?


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