Hiromura Seawall is a historic coastal embankment in Hirokawa Town, Arida District, Wakayama Prefecture. Designated as a National Historic Site of Japan, it is an important cultural heritage site that demonstrates how local communities have prepared for the threat of tsunamis for generations.
The seawall was constructed following the devastating tsunami caused by the Ansei-Nankai Earthquake of 1854. Its construction was led by Hamaguchi Goryo, a successful businessman and respected local leader who devoted his own resources to helping the people of Hiromura recover from the disaster.
Hamaguchi Goryo is also closely associated with the famous Japanese story of “Inamura no Hi,” or “The Fire of Rice Sheaves,” in which a local leader uses burning rice sheaves to warn villagers of an approaching tsunami. The Hiromura Seawall represents the next stage of that story: not only saving lives during a disaster, but also rebuilding the community and preparing it for future disasters.
More than 150 years after its construction, the Hiromura Seawall remains an important symbol of Hirokawa Town. Its effectiveness was demonstrated during the 1946 Showa-Nankai Earthquake, when the seawall helped prevent the tsunami from causing much greater damage to the town.
Today, the top of the seawall has been developed as a walking path. Local residents use it as a pleasant place for walks, while the site also serves as an important location for disaster-prevention education.
Nearby, the Inamura-no-Hi no Yakata museum introduces the history of Hamaguchi Goryo, the 1854 tsunami, and disaster preparedness. Guided explanations by local storytellers can provide visitors with a deeper understanding of the site’s historical significance.
The tsunami generated by the 1854 Ansei-Nankai Earthquake caused enormous destruction in Hiromura. Houses and farmland were washed away, leaving many residents without the means to support themselves. Some people were forced to leave the village, and the future of the entire community was placed in doubt.
Hamaguchi Goryo responded immediately. He used his own wealth to support disaster victims, providing assistance that included housing, farming tools, and financial support for merchants.
At the same time, he recognized that simply rebuilding the village was not enough. A similar tsunami could strike again in the future, so he decided to construct a large seawall that would protect the community.
Construction began in February 1855. More than 56,000 person-days of local labor were employed during the project, creating valuable work for residents whose livelihoods had been destroyed by the tsunami.
The project therefore had two purposes. It was a major disaster-prevention project, but it was also a way of supporting economic recovery and creating employment for disaster victims.
This approach is particularly remarkable from a modern perspective. Hamaguchi Goryo understood that effective disaster recovery required more than physical protection. People also needed jobs, homes, and the opportunity to rebuild their lives.
The Hiromura Seawall is an impressive earthen embankment approximately 640 meters long and 5 meters high. Its base is approximately 20 meters wide. Sand, gravel, and clay were carefully layered to create a strong barrier protecting the settlement behind it.
The scale of the structure demonstrates the considerable effort required to protect an entire community from tsunami waves. At the same time, the seawall was designed in harmony with the existing coastal landscape and earlier defensive structures.
On the seaward side of the seawall is an older stone embankment associated with the Hatakeyama clan, which was constructed during the medieval period. Hamaguchi Goryo’s seawall was built behind this older structure, creating a form of multiple-layered coastal defense.
The seawall also included a floodgate known as the “Akamon,” or Red Gate. This gate was designed to limit the flow of seawater into the settlement during high tides and tsunami events.
Trees and vegetation were planted around the embankment, including Japanese black pine, spindle trees, and wax trees. These plants helped form a coastal protection forest while also softening the appearance of the large earthwork.
The planting of wax trees was particularly ingenious. The fruits of these trees could eventually be used to produce material for candles, with the resulting income intended to contribute to the maintenance of the seawall.
This idea demonstrates how Hamaguchi Goryo considered the long-term sustainability of the project. The seawall was not viewed as a structure that could simply be built and forgotten; the community needed a way to maintain it for future generations.
Hirokawa Town lies at the innermost part of Yuasa Bay, an area that has historically been vulnerable to tsunami damage. The community had already experienced efforts to protect itself from the sea long before the construction of the Hiromura Seawall.
During the Muromachi period, the Hatakeyama clan constructed stone defenses along the coast, and these structures were repaired and modified over the centuries. However, the Hoei Earthquake of 1707 caused catastrophic damage, demonstrating the continuing power of tsunamis.
After the 1854 disaster, the construction of the Hiromura Seawall fundamentally strengthened the town’s defenses. The structure subsequently demonstrated its value during several major coastal disasters, including the high waves of 1913, the 1944 Showa-Tonankai Earthquake, and the 1946 Showa-Nankai Earthquake.
Its long history of protecting the community makes the seawall an important example of traditional Japanese disaster-prevention engineering.
The importance of the Hiromura Seawall goes far beyond its historical value. It remains an important place for learning about disaster preparedness and passing knowledge from one generation to the next.
Every November, the local community holds the Tsunami Festival. As part of the event, children participate in activities such as adding earth to the seawall. These activities help younger generations understand the importance of maintaining the structure and remembering the disasters experienced by their ancestors.
Educational programs are also conducted in cooperation with the Inamura-no-Hi no Yakata museum. Local storytellers share the history of the tsunami and explain the importance of being prepared for future disasters.
These activities have particular significance because the region remains vulnerable to major earthquakes and tsunamis associated with the Nankai Trough. The experience preserved at Hiromura demonstrates that disaster preparedness is not only about modern technology. It also depends on remembering past disasters and passing practical knowledge from generation to generation.
The Hiromura Seawall therefore serves as a bridge between the past and the future. Its history encourages visitors to consider how communities can prepare for natural disasters and recover when they occur.
Today, visitors can walk along the top of the Hiromura Seawall and experience its impressive scale while enjoying the peaceful coastal surroundings. The quiet landscape can make it difficult to imagine the devastation caused by the tsunami of 1854, making the historical story all the more powerful.
Walking along the embankment provides an opportunity to think about the people who built it, the families whose lives were transformed by the tsunami, and the generations who have continued to maintain and protect the structure.
For international visitors, the site offers a valuable perspective on Japanese disaster-prevention culture, traditional engineering, community resilience, and local leadership.
The Hiromura Seawall is more than an old coastal embankment. It is a living symbol of disaster prevention, recovery, and community resilience. Built after one of the most devastating tsunamis in the region’s history, it protected the town for generations and continues to educate people today.
Its story is closely connected with Hamaguchi Goryo and the famous “Inamura no Hi” story, but the seawall also tells a broader story about how ordinary communities can respond to natural disasters with determination, cooperation, and long-term planning.
When visiting Hirokawa Town, take time to walk along the Hiromura Seawall and visit the nearby disaster-prevention museum. Together, these sites provide a meaningful introduction to the history of tsunamis in Japan and the enduring wisdom of the people who worked to protect their community.
Surrounded by the calm scenery of the coast, the seawall quietly continues to tell its story—a story of remembering the past, protecting the present, and preparing for the future.