Castle Day (Shiro no Hi)

What Is Castle Day?

Every April 6th is "Castle Day" (Shiro no Hi) in Japan. The date comes from a pun reading 4 as "shi" and 6 as "ro," making "shiro" (castle), and it was established in 1974 by the Japan Castle Foundation (Nihon Jokaku Kyokai). It's a day to deepen understanding of castles, which convey Japan's history and culture, and to think about preserving and passing them on. In 1990, the city of Himeji in Hyogo Prefecture also designated this day as "Castle Day," and with the date falling in cherry blossom season, events are held at castles across Japan.

Castles as Defensive Systems

Castles were strongholds built with many clever uses of terrain and design in preparation for battle.

• "Nawabari" (castle layout): The layout and design of a castle is called "nawabari." Winding passages and the square, walled "masugata koguchi" gates were designed to break the momentum of attacking forces and let defenders strike them from all sides.
• The twelve surviving original keeps: Only 12 castles still have keeps built in the Edo period or earlier: Himeji, Matsumoto, Hikone, Inuyama, Matsue, Hirosaki, Maruoka, Bitchu Matsuyama, Marugame, Matsuyama, Uwajima, and Kochi. They are precious buildings that survived the Meiji-era castle abolition order and wartime destruction.

How Stone Walls Were Built

The stone walls built in an age without heavy machinery are full of artisans' skill.

• "Ogi no kobai" (fan-shaped slope): The beautiful curve of a stone wall, gentle at the bottom and nearly vertical toward the top, is called "ogi no kobai." It made the walls harder to climb and is also said to help keep them from collapsing.
• Nozurazumi, uchikomihagi, and kirikomihagi: Building methods changed over time, from "nozurazumi," stacking nearly unworked natural stones; to "uchikomihagi," shaping the stones' corners to reduce gaps; to "kirikomihagi," precisely cutting stones to fit with no gaps. Looking at a stone wall can sometimes give you a clue to when it was built.

Interesting Facts About Castles

• The whiteness of the "White Heron Castle": Himeji Castle, a World Heritage Site, owes its whiteness to "shiro-shikkui sonurigome," a technique of coating walls and even roof-tile joints with white lime plaster. Plaster also has the advantage of resisting fire. In 1993, Himeji Castle and Horyu-ji became Japan's first World Cultural Heritage Sites.
• Lords lived in the "goten" palace: The keep was not where the lord lived day to day. Lords normally lived and conducted government business in the "goten" palace within the castle grounds.
• The castle abolition order: Under the so-called castle abolition order of 1873 (Meiji 6), castles were divided into those to be kept and those to be abolished, and the buildings of abolished castles were torn down or sold off.
• Azuchi Castle's keep: Azuchi Castle, built by Oda Nobunaga, is said to have had a lavish keep decorated with gold leaf and vivid colors. Castles were both military bases and symbols of a ruler's authority.
• Japan's 100 Fine Castles: The Japan Castle Foundation selected the "100 Fine Castles of Japan" in 2006 and the "Continued 100 Fine Castles of Japan" in 2017. Touring castles and collecting the stamps available at each one is a popular pastime.

Tips for Marking Castle Day

• Visit a nearby castle or castle ruin and take a close look at how its stone walls and gates are built
• Browse the lists of the "100 Fine Castles" and "Continued 100 Fine Castles" and find your next favorite castle to visit
• Look into donation programs that support castle restoration and think about how cultural properties can be passed on to the future
• Take a stroll at a castle known for its cherry blossoms and enjoy some hanami at the same time

Like a Stone Wall Built One Layer at a Time

April 6th is a day to turn our attention to castles that have stood through long years. Just as a sturdy stone wall is made by carefully stacking stone upon stone, small daily efforts add up to great results. In this season of cherry blossoms and castle keeps, why not visit a castle near you and experience the wisdom and skill of those who came before?