When we think of Aizu's symbol, it's the beautifully towering 'Tsurugajo (Aizuwakamatsu Castle)'.
Have you ever looked up at the castle and felt, 'How beautiful,' when you saw the wave-like roofs stacked upon each other and the protruding bay windows?
In fact, that elegant design hides a terrifying military calculation that is not just decoration.
This time, we will guide you through the deep codes and mysteries of Tenshu architecture that will completely change your perspective on the castle.
[Mystery ①] Why did only Nobunaga write 'Lord of Heaven'?
The tallest and largest building at the center of a castle is often referred to as the 'tenshukaku'.
In fact, in historical records of castles, this term is mostly written as 'tenshu'. However, did you know that in Japan's history, only Azuchi Castle, built by Oda Nobunaga, used the kanji 'ten-shu'?
There are various theories, but it is said that Nobunaga, who feared neither gods nor Buddha, used this to assert that 'he is the lord of the world (heaven)'. Can't you see the intense ego and pride of a Warring States general reflected in just a single character difference?
[Mystery ②] The changed 'shape of the tenshu' after the Battle of Sekigahara
There are broadly two trends in the silhouette (shape) of castles. When viewed alongside the historical context, it becomes clear what the daimyo of the time were thinking.
Two trends of tenshu
・Bōrō-gata (望楼型) tenshu:
This is a castle from an older era. It has a large foundation house with one to two stories, topped with a 'watchtower (bōrō)' for distant viewing. Even if the lower floors are uneven and irregularly shaped, it is a wild construction that can forcibly place a tower on top, emphasizing practical combat.
・Sōtō-gata (層塔型) tenshu:
This is a new style that emerged after the Battle of Sekigahara. From the first floor to the top floor, square boxes are stacked in a smart and beautiful shape, gradually decreasing in size. It shows a shift from a 'fortress for fighting' to a 'symbol of power (appearance)' in an era of peace. (Currently, Tsuruga Castle also has this beautiful silhouette of the sōtō-gata.)
The beautiful roof hides a zero-dead-angle space for snipers
The triangular decorations found all over the castle's roof are called 'hafu'. Various types, such as chidori hafu and kara hafu, combine to create stunning beauty, but if you were a soldier attacking this castle, there would be nothing more terrifying.
This is because the backside of these hafu and the protruding 'bay windows (demado)' are packed with functions to eliminate blind spots and shoot enemies directly below or to the side.
Terrifying gimmicks for interception
・Samazama (狭間):
Small round, triangular, or square holes opened in the wall. From here, one could observe the outside and safely snipe with arrows or guns.
・Ishiotoshi (石落とし):
A terrifying trap where part of the floor of the bay window opens, allowing stones to be dropped or boiling water to be poured down.
From the outside, it looks like a "beautiful decoration," but from the inside, it is a "perfect fortress." This gap is what makes Japanese castle architecture the most academically interesting.
Fieldwork to decipher the "hidden face" of history
How was it?
At "Tabinoito," we offer a tour in the academic style that guides you through the duality of the "beauty" and "horror" of such castle architecture with the vivid explanations of our guides.
"So that’s where they were aiming with guns!" "Is that where the stones fall from this bay window!"
Why not look up at Tsuruga Castle from the perspective of both the attackers and defenders? We look forward to the day we can solve the mysteries of history together with you.
