古代山城 (Kodai Yamajiro)-Ancient mountain castles
中世山城 (Chusei Yamajiro)-medieval mountain castles
近世山城 (Kinsei Yamajiro)-early modern mountain castles
平山城 (Hirayamajiro)-a castle built on a hill in a plain
平城 (Hirajiro)-a castle built in a plain
城柵 (Jyosaku)- Ancient Guardian Office
Ancient Fortress Foreign Style was built in Order to Counter the Invading Forces from the Tang and Baekje
Ancient mountain castles in Japan are built in Asuka to Nara period in the West Japan. The mountain castles have many similarities with Korean Peninsula castles because Baekje nobility that had been exiled from the current Korean Peninsula was the guidance of architecture.Typical one is Onojo. The castles are only barricaded in the war times, and in peacetimes people lived in the foothills. Ancient mountain castles which are mentioned in “Chronicles” or “Shoku Nihongi” are categorized as 古代山城 (Kodai Yamajiro), and ones not showed up in the records are classified as “Kōgoishi formula Fortress”.
(Photo Kino castle)
城柵 (Jyosaku)- Ancient Guardian Office is a Castle for the Conquest of the Indigenous Ezo of Japan
Through the Heian era from the Nara period, ancient mountain fortress was built in the West Japan. On the other hand, in North part of Japan was still a land of the natives (Emishi). Japanese central government were attacking the natives and created Jyosaku, guardian Offices, there. Jyosaku castles did not have storing defense power like mountain castles in the west japan. Typical Shirosaku is Tagajo Sendai.
Medieval Fortress was built from the late Heian period until the end of the Warring States
While the ancient fortress was for fighting against Taito-Baekje, from the late Heian period, domestic situation became unstable. In Northern and Southern Dynasties era, Southern side Godaigo forces started to built mountain castles to counter Northern side Kamakura dynasty in the West Japan. Kusunoki Masashige (the Southern side) built “Chihaya Castle” and “Akasaka Castle” and following samurais followed him to build similar fortress in various places.
In Warring States, old style mountain castles became inconvenient. Samurais started new style castles. 中世山城 (Chusei Yamajiro)-medieval mountain castles have a residential area within castles. One of the most famous samurais, Takeda Shingen was born in medieval mountain castle “Yogaiyama Castle”.
(Photo Takeda Castle)
Sensational Nobunaga’s Azuchi Castle Made Stone Wall and Roof Tiled Castle Became a Japan’s Typical Castle Design
Castle with a donjon was built before Azuchi Castle, but Azuchi castle was said first time a castle with a full-fledged castle tower in Japan. 近世山城 (Kinsei Yamajiro)- an early modern mountain castle is fortress that was built in to the early Edo period from the late Azuchi Momoyama period. Also it appeared 近世山城 (Kinsei Yamajiro) like Azuchi Castle with a graceful tower contrary to a rational medieval fortress. These castles are designed for comfortable living and built on more accessible gentle mountains, but on the other hand it is venerable for intruders compare to 中世山城 (Chusei Yamajiro)-medieval mountain castles.
(Photo Azuchi Castle restoration model)
Towards a Peaceful Time Castle became a Huge City Itself
In the end of the Warring States power structure became clear. Especially more powerful lords started to build huge castle enclosing the castle town. Odawara Castle was at first mountain castle, but it was expanded to include the city beneath and castle came down from the mountain and became a 平山城 (Hirayamajiro)-a castle built on a hill in a plain. Azuchi Castle and Nijo Castle was fortification of Nobunaga Oda (current Nijo Castle of castle Tokugawa) and will become a model for subsequent castle architecture.Such as Edo Castle, Osaka Castle, and Nagoya Castle are classified as 平山城 (Hirayamajiro).
(Photo Nagoya Castle)
Summary of Japan’s Castles
In Japan, style of castle transformed from mountain castles to 平山城 (Hirayamajiro)-a castle built on a hill in a plain, or 平城 (Hirajiro)-a castle built in a plain. Castles contain existing tower is only 12 castles in Japan. These are mostly 平山城 (Hirayamajiro)-a castle built on a hill in a plain or 平城 (Hirajiro)-a castle built in a plain. We can not see authentic buildings of mountain fortress these days. Although, if you know the history and structural patterns of castles you can imagine the castle offensive or a mountain of defense from the terrain of the Middle Ages.