Ozu Castle Sannomaru South Corner Tower

Ozu Castle Sannomaru South Corner Turret: The Oldest Surviving Structure of a Beloved Shikoku Castle

Standing quietly within the grounds of what was once the outer compound of Ozu Castle, the Sannomaru Minami Sumi Yagura (South Corner Turret of the Third Bailey) is a remarkable survivor of feudal-era military architecture in Ehime Prefecture. Designated as an Important Cultural Property of Japan, this two-story turret is the oldest existing building in the entire Ozu Castle complex, predating even the other three surviving turrets. Located in the castle town of Ozu—a charming riverside settlement often called the "Little Kyoto of Iyo"—the turret offers visitors a rare and authentic glimpse into the defensive engineering and craftsmanship of Edo-period Japan.

Historical Background

Ozu Castle traces its origins to 1331, when Utsunomiya Toyofusa, a warrior dispatched to Iyo Province, established a fortification on Mount Jizo at the confluence of the Hijikawa and Kumekawa rivers. Over the following centuries, the castle was expanded and modernized by a succession of lords, most notably Todo Takatora, the renowned castle-building strategist, who transformed it into a fully-fledged early modern castle during the late 16th century.

In 1617, Kato Sadayasu entered Ozu Castle and established the Kato clan's rule over the 60,000-koku domain. The Kato family governed Ozu for the remainder of the Edo period, and it is during this era that the castle's surviving turrets were built or rebuilt. The South Corner Turret's original construction date is unknown, but a ridge plaque (munafuda) preserved with the turret records that it was destroyed by fire in 1722 (Kyoho 7) and rebuilt 44 years later in 1766 (Meiwa 3).

The ridge plaque also reveals that the domain was facing financial difficulties at the time of reconstruction. To reduce costs, the authorities employed domain officials as craftsmen (yakujin kosho) and used an economical timber selection: Japanese hemlock (tsuga) for critical structural joints and pine for the main pillars. Despite these economies, the turret was built to exacting military standards, with sophisticated defensive features concealed within its walls.

Why It Was Designated as an Important Cultural Property

The Sannomaru South Corner Turret was designated as a national Important Cultural Property on June 18, 1957, along with the three other surviving turrets of Ozu Castle (the Kitchen Turret, the Balustrade Turret, and the Owata Turret). While none of these structures date from the castle's original construction, they represent invaluable physical evidence of the castle's Edo-period configuration and the military architecture of a mid-sized feudal domain.

The South Corner Turret holds particular significance as the oldest of the four surviving structures, having been rebuilt in 1766. Its accompanying ridge plaque, which documents the circumstances of its reconstruction including the financial constraints of the domain, is also designated as an Important Cultural Property. Together, the turret and its plaque provide a vivid historical record of castle maintenance during a period of economic difficulty.

The turret is also notable for retaining its original defensive features intact, including concealed loopholes and bullet-resistant walls, offering researchers and visitors an authentic example of mid-Edo period military engineering.

Architectural Highlights and Defensive Features

The South Corner Turret is a two-story, two-tier (niju nikai) structure with a tiled roof (hongawarabuki). It was positioned at the southern corner of the outer moat of the third bailey (sannomaru), serving as a watchtower and defensive strongpoint on the castle's perimeter.

One of its most distinctive external features is the pair of hakama-goshi-style stone-dropping chutes (ishiotoshi) at both ends of the structure. These projecting bays allowed defenders to drop stones or pour boiling water on attackers attempting to scale the walls below. Three stone-dropping positions are incorporated in total.

Inside, the turret features taiko-kabe (drum walls)—thick, bullet-resistant walls reinforced with embedded bamboo tubes. Most intriguingly, three kakushi-zama (hidden loopholes) are built into the interior walls. These firing ports are completely concealed from the outside by a smooth layer of plaster, making them invisible to approaching enemies while allowing defenders to open fire with muskets at close range.

The turret underwent a full disassembly restoration (kaitai shuri) in 1965, ensuring the preservation of its original structural elements and defensive installations for future generations.

Visitor Information

The South Corner Turret is located within the Sannomaru Minami Sumi Yagura Park, popularly known as "Otonosama Koen" (Lord's Park). The park also contains the Former Kato Family Residence, a registered tangible cultural property built in 1925 by a descendant of the last Ozu domain lord. The residence blends traditional Japanese aristocratic architecture with Western-style modernist elements and was even used as a filming location for the beloved movie series "Otoko wa Tsurai yo" (It's Tough Being a Man) in the 1970s.

The turret's exterior and interior are open to the public. Visitors can climb to the second floor and observe the hidden loopholes, drum walls, and stone-dropping chutes firsthand. The park is a short walk from the main Ozu Castle complex and offers views of both the turret and the reconstructed castle tower in the distance.

Ozu Castle itself (main tower and attached turrets) is open daily from 9:00 AM to 5:00 PM (last entry 4:30 PM). Admission for the castle is 550 yen for adults and 220 yen for children. A combined ticket covering Ozu Castle, Garyu Sanso villa, and Bansenso is available for 1,100 yen (adults). The NIPPONIA HOTEL Ozu Castle Town also offers exclusive dining experiences inside the South Corner Turret itself—a rare opportunity to dine within a nationally designated Important Cultural Property.

Access

The turret park is located in the Ozu district of Ozu City, Ehime Prefecture. From JR Iyo-Ozu Station on the Yosan Line, the castle area is approximately a 20-minute walk or a 5-minute taxi ride. The Guririn Ozu circular bus runs from "Ozu Ekimae" to "Ozu-jo Mae" in about 10 minutes; from there, the turret park is a short walk south. By car, take the Matsuyama Expressway to the Ozu Konan Interchange, from which the castle area is about 10 minutes away. Free parking is available at the Ozu City Tourist Parking Lot No. 1.

Surrounding Attractions

Ozu is a treasure trove of cultural heritage sites that can easily fill a full day of exploration. Garyu Sanso, an exquisite sukiya-style villa perched on the banks of the Hijikawa River, is widely regarded as one of the finest examples of Meiji-era residential architecture in Japan and lies just a 12-minute walk from the castle. The historic Ohanahan Street preserves the atmosphere of an Edo-period castle town with its traditional merchant houses and earthen walls.

The Hijikawa River itself is a highlight, famous for its summer cormorant fishing (ukai) tradition and the autumn imotaki (taro stew) gatherings along its banks. The reconstructed four-story wooden tower of Ozu Castle, completed in 2004 through citizen donations, is a must-see and offers panoramic views of the surrounding mountains and river valley. For those interested in staying overnight, the Ozu Castle Stay program allows guests to sleep inside the castle tower itself—an experience available nowhere else in Japan.

Bansenso, a recently restored historical villa, and the Ozu Historical Exploration Hall round out the town's cultural offerings. The local specialty wagashi (Japanese sweets) shop Murata Bunpuku Roshi, near the Hijikawa Bridge, is renowned for its gesso mochi, a delicate kinako-dusted confection with sweet bean paste.