The Outer Moat in the 1940’s: Stories from Mr. Sakai

The area in front of JR Ichigaya Station, one of the places where the outer moat remains. The water surface reflects the surrounding buildings.

Before Tokugawa Ieyasu built Edo Castle, the Musashino Plain—what would later become known as Edo—was a wetland thick with reeds. Constructing the castle and securing a livable space for Tokugawa’s retainers was a major undertaking. The transformation of Tokyo into the world-class metropolis it is today owes much to its network of waterways, including the outer moat.

Sotobori (outer moat), refers to the perimeter of the fortification trenches that encircled Edo Castle (now the Imperial Palace). It includes parts of the Nihonbashi River, Sotobori River, Shiodome River, and the stretch from Iidabashi to Yotsuya, Akasaka-mitsuke, and even the downstream areas of the Kanda River. If you ride the JR Chuo Line between Iidabashi and Ichigaya, the pond-like body of water visible from the train is a remnant of the outer moat.

In this article, we speak with Mr. Toshiaki Sakai, who spent his childhood growing up near the outer moat in the 1940s and who has observed its ever-changing face. Join us as we rediscover Tokyo’s history and hidden charm through his reminiscences.

Did Fireflies Really Fly Around the Outer Moat?

Born in 1939, Mr. Sakai still lives near the outer moat and serves as a board member of the Iidabashi West Exit Redevelopment Association, keeping a close eye on life in the area. When he was a child, the outer moat was full of natural beauty, teeming with wildlife, and served as a playground for local children—something hard to imagine today.

Tokyo Daijingu, once known before the war as “Iidabashi Daijingu,” is also called “Tokyo’s Ise Shrine.”

“When I was about 10 years old, one of my favorite daily pastimes was going out with friends to catch fish using a yotsude-ami, a special kind of 4-poled river fishing net,” Mr. Sakai recalls. “We would cross the Chuo Line train tracks and wade into the outer moat, catching all kinds of creatures like crucian carp and eels. There was plenty of aquatic vegetation, and when we brought the fish home, we’d put the plants in the bucket too so the fish wouldn’t run out of oxygen.”
The part of the moat Sakai fished in is near Tokyo Daijingu (Fujimi 2-chome, Chiyoda-ku) close to Iidabashi Station.

Iidabashi Ramla shopping center as seen from the Kagurazaka-shita intersection. This area was once part of the outer moat, where small shrimp could be caught.

“Iidabashi Ramla, the shopping center next to Iidabashi Station, used to be part of the outer moat section called Iida Moat. Although it is now filled in, it was once a great spot for catching small shrimp. I’d take the shrimp home, and my family would simmer them in soy sauce and sugar. That delicious sweet and savory flavor is one of my best memories of the outer moat.”

According to some, fireflies once lived in the section of the moat near Tokyo Daijingu, just a short distance from Iidabashi Station.

Why Yotsuya Subway Station Is Above Ground

After the war, the area around the outer moat was a popular spot for kids to go swimming and enjoy nature.

“The present-day Kagurazaka was mostly destroyed by the Tokyo air raids. Especially the north side of the outer moat, near Iidabashi, suffered severe damage. In contrast, the south side of the moat—around where Iidabashi Station now stands—was protected from the spreading fires thanks to the water boundry of the moat. From the rooftop of the former Tokyo Police Hospital (currently the Fujimi-cho branch of the United Church of Christ in Japan), you could see Mount Fuji. As kids, we would often fly kites there,” says Mr. Sakai.

From Kioi-cho looking toward Yotsuya Station, you can spot the Sophia University athletic field where some of the old stone banks of the moat remain.

The area stretching from Akasaka-mitsuke to the Yotsuya Moat (Sanada Moat—what is now the Sophia University athletic grounds and the area near Yotsuya Station) was known for having especially beautiful views of the outer moat. Although the Yotsuya Moat has since been filled in, the stone embankments along Sophia University’s grounds offer a glimpse into its past. The train tracks used to run right next to the water.

Interestingly, the Marunouchi Line’s Yotsuya Station is above ground, despite it being a subway station. This is because it was built within the former Yotsuya Moat. This is a rare example of a subway station located above ground—and perhaps one of the few chances we still have to feel a connection to the outer moat today.

Yotsuya Station is a rare example of a station built inside the outer moat.

“The area around Iidabashi Station used to be bustling place because of the lumberyards. There was even a police dojo for kendo and judo practice. There was a boat landing at what is now Iidabashi Ramla shopping center, and you could take a yakatabune (traditional pleasure boat) all the way to Ryogoku,” he noted.

Mr. Sakai’s anecdotes are testament to how the outer moat once served as part of the city’s natural environment, and served as an important transportation route that supported Tokyo’s growth and development.

The Community Bonds Fostered by the Outer Moat

As times have changed, not only has the scenery of the outer moat evolved, but so too have the lives of the people living in the waterfront areas. Mr. Sakai shares some memories while reflecting on the changing scenery of the surrounding areas.

“There was once a strong sense of community in Fujimi-cho. We used to pound mochi together as part of the neighborhood association. We also held traditional street fairs and festivals with portable shrines every year.”

A narrow alley in Kagurazaka, where traces of the past still remain. This once-thriving geisha district was home to many more traditional restaurants where entertainment took place.

“Tokyo is a city where new things are constantly being built, and that’s a good thing in many ways. But when long-standing shops and familiar places disappear, there’s an undeniable sense of loss. The long-beloved sweets shop Kinonozen in Kagurazaka closed in 2022. You no longer see the geisha on their way home after an evening at the ozashiki. I miss the lively sound of the shamisen that once filled the streets.”

Of course, all across Japan, small family-run businesses—fishmongers, butchers, greengrocers—are disappearing with the rise of large supermarkets and commercial complexes. What gives a neighborhood its true character may be the unique scenery, like that of the old moat, and the warmth and connection of the people who live there.

Leaving Beautiful Waterside Scenery to the Next Generation

In winter, migratory birds such as the Northern Shoveler come to rest on the waters of the outer moat. They can still be seen around Ichigaya Station today.

“There were once places within the outer moat where migratory birds would arrive in winter. And along the Chuo Sobu Line, the waterside cherry blossoms make for a stunning spring scene. Even in a city like Tokyo, there aren’t many places where people can enjoy such natural beauty so close to where they live and work. Personally, I love taking boats when I travel: I’m drawn to the water. I believe people are instinctively comforted by waterside scenery. That’s why I find myself wondering whether there’s a way we can pass on treasures like the outer moat to future generations.”

Sotobori Park, a beloved cherry blosoom viewing spot where the pink blooms reflect on the water’s surface.

Along the outer moat stretching from JR Iidabashi Station toward Ichigaya, the rows of cherry trees bloom each spring, offering a moment of calm and comfort to those passing by. Planted by residents of the Iidabashi area, these cherry trees reflect over 50 years of local dedication to preserving the outer moat’s scenic beauty.

“The cherry trees along the banks of the moat are now reaching the end of their lifespan. They have faced many challenges such as damaged branches from typhoons and heavy rains. Some trees have weaknened due to age and a few have even fallen down. Yet, this remains one of the rare and precious spots in Tokyo where cherry blossoms and water’s edge blend seamlessly with the city.

While urban development may sometimes involve filling in moats to create more habitable space, I hope those areas where we can still enjoy views of the water and springtime cherries from the embankments won’t disappear.

The outer moat has preserved its rich history and allure since the Edo period. If residents, businesses, and local government work together to protect this legacy while creating enjoyable waterside facilities, I believe we can make the city even more appealing.”

These words carry a heartfelt desire to pass down the lifestyle connected with the outer moat to future generations.

Conclusion

From Mr. Sakai, who has witnessed the changes of the outer moat since the postwar period, we recognize that the outer moat area has been a familiar and integral part of life for the people living in Tokyo. Built during the Edo period and having endured the trials of history and wars, Mr. Sakai’s stories inspire a renewed hope that the outer moat will continue to live on as a cherished presence in our everyday lives.

The outer moat and the high-rise buildings reflect a landscape carefully shaped and treasured by the people of Tokyo over hundreds of years.

The coexistence of Edo-period stone embankments filled with water and the modern cityscape of towering buildings is distinctive. The outer moat is a place where we can witness the depth of Japan’s unique history.

A meaningful bond between people and the waterside can only endure if we protect and nurture this unique environment and pass this legacy on to future generations. We can start by revitalizing the outer moat with sparkling clean, flowing water, just like in the past, while making the most of the current landscape and resources. It’s an mission we can all contribute to.