Imabari Castle

Timeline

1. 1600

   Takatora Installed

   Following the Battle of Sekigahara, Tokugawa Ieyasu grants the 200,000-koku Iyo Province to Todo Takatora to control the Seto Inland Sea and check western daimyo

2. 1602

   Construction Begins

   Todo Takatora begins building Imabari Castle under chief engineer Watanabe Satoru, breaking convention by choosing a coastal flatland site over a defensible mountain stronghold

3. 1604

   Castle Completed

   Imabari Castle is completed featuring three concentric seawater moats and the prototype of the layer-style tower keep, becoming one of Japan's three great sea castles

4. 1609

   Takatora Transferred

   Todo Takatora is transferred to Tsu Castle in Ise Province; the tenshu is reportedly dismantled and relocated to Tanba Kameyama Castle as recorded in the Kansei Choshu Shokafu

5. 1635

   Hisamatsu-Matsudaira Clan

   Todo Takayoshi is transferred to Iga-Nabari and replaced by Matsudaira Sadafusa of the Hisamatsu-Matsudaira clan, who rule Imabari for the rest of the Edo period

6. 1869

   Castle Abolished

   Even before the formal abolition of the castle system in the Meiji Restoration, most buildings are dismantled, leaving only the stone walls and inner moat

7. 1871

   Bugu-yagura Destroyed

   A fire ignites gunpowder stored inside the surviving north corner armory turret of the ninomaru, destroying the last original superstructure of the castle complex

8. 1953

   Ehime Prefectural Historic Site

   On October 9, the surviving Edo-period stone walls and inner moat are formally designated as an Ehime Prefectural Historic Site for preservation

9. 1980

   Replica Keep Constructed

   A five-story, six-floor replica keep is constructed in reinforced concrete on the former site of the north corner turret in the honmaru

10. 1985

    Okane-yagura Restored

    The east corner turret is reconstructed as the Okane-yagura with exterior facade restoration based on historical photographs from the late Edo period

11. 1990

    Yamazato-yagura Wooden Restoration

    The west turret is reconstructed in wood at the western corner of the ninomaru, marking the first fully-wooden restoration project at Imabari Castle

12. 2006

    Top 100 Japanese Castles

    On April 6, Imabari Castle is selected as the 79th of the Top 100 Japanese Castles by the Japan Castle Foundation, gaining nationwide heritage recognition

13. 2007

    Kurogane Main Gate Restored

    In September, the Kurogane Main Gate and five connected tamon yagura are reconstructed in wood based on archaeological excavation, and the Todo Takatora statue is erected

Detailed History

The history of Imabari Castle begins in 1600, the year of the Battle of Sekigahara. Tokugawa Ieyasu granted the 200,000-koku Iyo Province to Todo Takatora (1556-1630) with orders to control Seto Inland Sea shipping and check the influence of western daimyo, particularly Fukushima Masanori at Hiroshima Castle. Takatora initially based himself at Kokufu Castle atop Mount Karako several kilometers inland, but soon recognized its limitations and made the radical decision to build a new coastal fortress — a break from military thinking that prioritized high ground. Construction began in 1602 under engineer Watanabe Satoru, and the new Imabari Castle was completed in 1608, six years after construction began. The result was a masterpiece of early modern castle architecture: three concentric seawater moats, high walls with the inubashiri walkway, and the prototype layer-style tower keep on a rectangular foundation. The castle featured the daimyo's residence in the second enclosure, retainer quarters within the inner moat, samurai residences within the outer moat, nine gates, and twenty turrets — a vast complex with an internal anchorage where ships could dock directly inside the walls. In 1609 Takatora was transferred to Tsu Castle, and the tenshu is documented in the Kansei Choshu Shokafu as dismantled and relocated to Tanba Kameyama Castle. Takatora's adopted son Takayoshi inherited the Imabari domain as a 20,000-koku exclave until 1635, when he was replaced by Matsudaira Sadafusa of the Hisamatsu-Matsudaira clan, who ruled until the Meiji Restoration. The complex was maintained through 260 years of Tokugawa peace, but in 1869 most buildings were dismantled. Only the bugu-yagura survived as an army garrison, but in 1871 a fire ignited its gunpowder stores, destroying the structure. The Edo-period stone walls and inner moat were designated an Ehime Prefectural Historic Site on October 9, 1953. A five-story replica keep was built in reinforced concrete in 1980. The Okane-yagura (1985 exterior), Yamazato-yagura (1990 wooden), and the Kurogane Main Gate with five tamon yagura (September 2007 wooden) followed in stages. A bronze statue of Todo Takatora was erected in 2007. In April 2006, Imabari Castle was selected as the 79th of the Top 100 Japanese Castles.

Cultural Significance

Imabari Castle stands as the foremost of Japan's three great sea castles (Mizujiro), alongside Takamatsu Castle in Kagawa and Nakatsu Castle in Oita, distinguished by moats fed with seawater. Its builder, Todo Takatora (1556-1630), is recognized as one of the foremost castle architects of early Edo period Japan. His career spanned Uwajima, Ozu, Imabari, Tsu, and Iga Ueno Castles, making him the most prolific designer of his generation. Imabari was where Takatora first deployed the layer-style tower keep, in which a rectangular foundation supported a keep of standardized prefabricated components. This solved structural weaknesses of the earlier prospect-style keep, which suffered from attic-floor irregularity and vulnerability to wind and earthquakes. Takatora exported this technique to Edo Castle itself, establishing the dominant tenshu form for the rest of the early modern period. The inubashiri walkway pioneered here also influenced later sea castle construction. The castle was designated an Ehime Prefectural Historic Site in 1953 and selected as the 79th of the Top 100 Japanese Castles in 2006. Imabari promotes itself as a maritime city, regarding the castle as a symbol of its maritime heritage. Its location at the Shikoku gateway to the Shimanami Kaido cycling route makes it a magnet for travelers combining sightseeing with the cycling pilgrimage.

Architectural Details

Imabari Castle occupies an irregular footprint of approximately 400 meters east-to-west by 500 meters north-to-south, structured around three concentric moats: inner (uchibori), middle (nakabori), and outer (sotobori). Although the castle sits slightly inland, all three moats connect to the Seto Inland Sea and fill with seawater — exceedingly rare in Japanese castle design. The inner moat exceeds 60 meters wide, and a ship anchorage historically existed within the second enclosure. The layout is concentric, with honmaru, ninomaru, and sannomaru protected by nine gates and twenty turrets. The surviving originals are the stone walls and inner moat of the honmaru and ninomaru. Walls reach approximately 13 meters in maximum height, with sangi-zumi interlocked corner stones representing a valuable example of early modern masonry. To address the soft coastal foundation, Todo Takatora introduced the inubashiri — a 2-meter-wide flat platform at the wall base — preventing collapse during ground settlement. Reconstructions include the five-story replica keep (1980, reinforced concrete, ~23 meters tall, not historically faithful), the Okane-yagura (1985 exterior), the Yamazato-yagura (1990 wooden), and the Kurogane Main Gate with five tamon yagura (September 2007 wooden, based on excavation). The gate features iron-plated doors with a ceremonial structure.