Reclaimed land (umetatechi) is ground created by filling shallow sea with soil, sand, and rock. Japan has practised it since the Edo period, and about 250 square kilometres of Tokyo Bay is now reclaimed. Today these waterfront districts, from Toyosu to Harumi, host large-scale residential developments and continue to expand.
Key Facts at a glance
- Japanese term: 埋立地 (umetatechi), meaning “reclaimed land”
- Reclaimed area of Tokyo Bay: about 250 square kilometres, roughly 15% of the original bay (as of 2026)
- First major Tokyo reclamation: the 1590s, when Tokugawa Ieyasu filled the Hibiya Inlet to build Edo
- Main reclaimed residential districts: Toyosu, Harumi, Ariake, Odaiba, Tsukishima, Kachidoki, Shinonome
- Harumi Flag: about 5,632 homes on roughly 18 hectares; occupancy began January 2024
- Largest current plan: the Tokyo Bay eSG Project, about 1,000 hectares, announced April 2021
What is reclaimed land (umetatechi) in Japan?
Reclaimed land is land that people create by filling in or extending a body of water, such as a bay or coastline. The Japanese word is 埋立地, or umetatechi. Builders use materials like soil, sand, and rock. This means the shoreline you see in Tokyo Bay today looks very different from how it looked a few centuries ago.
Reclamation has served clear practical purposes throughout Tokyo’s history. It has secured harbours, made room for a growing city, and provided large flat sites for factories and, more recently, homes. In recent decades, old industrial and warehouse zones along the bay have been cleared and rebuilt as residential areas. Because large inland plots are hard to find in central Tokyo, these waterfront sites have become a natural home for new development.
How long has Japan been reclaiming land?
Land reclamation in Japan dates back centuries, with Tokyo Bay a clear example. When Tokugawa Ieyasu entered Edo Castle in 1590, the land around it was too small for a city. Soon after, the Hibiya Inlet was reclaimed to build a town, and the Onagi Canal was dug, with the dredged soil used to fill nearby land. This was the first reclamation work in the Koto area.
The pace then grew over time. About 2,700 hectares were reclaimed in the Tokyo Bay area during the Edo era across roughly 270 years, and about 6,000 hectares from the Meiji era to the present. By 2012, Tokyo Bay included about 249 square kilometres of reclaimed land. In other words, reclamation is not a modern experiment in Tokyo. It is a long, continuous practice that shaped the modern map of the bay.
出典：国土交通省 関東地方整備局 東京港湾事務所ウェブサイト「東京港の変遷」（https://www.pa.ktr.mlit.go.jp/tokyo/history/）をHousing Japanが加工（英語訳および造成年代の色凡例の翻訳を追加）。
Source: “Transition of Tokyo Port,” Tokyo Port Office, Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism (MLIT) (https://www.pa.ktr.mlit.go.jp/tokyo/history/). Adapted by Housing Japan, with English translations and the reclamation-era colour legend translated.
What has been built on Tokyo’s reclaimed land?
Several of Tokyo’s well-known bay districts sit on reclaimed land. Each shows how former industrial sites became places where people now live and visit.
Toyosu
Toyosu in Koto Ward was once an industrial area and is now one of the bay’s busier districts. It is home to a concentration of high-rise condominiums, including City Towers Toyosu the Symbol and Toyosu Ciel Tower. The area also draws visitors to teamLab Planets, which opened in 2018, and to the Toyosu Market, which took over wholesale fish trading from Tsukiji the same year. In February 2024, Toyosu Senkyaku Banrai opened beside the market, an Edo-themed dining and hot-spring complex with about 70 stores. Tsukishima and Kachidoki sit close by, with easy access toward Ginza.
Harumi
Harumi has changed quickly since Harumi Island Triton Square, a mixed office and residential complex, opened in 1998. Its biggest recent change is Harumi Flag, built on the site of the athletes’ village for the Tokyo 2020 Olympic and Paralympic Games, held in 2021. After the Games, the buildings were renovated into homes, with around 5,632 condominium and rental units on roughly 18 hectares, and occupancy began in January 2024. New elementary and junior high schools opened in April 2024, and the district was planned to house about 12,000 people.
Ariake and Odaiba
Further out, Ariake and Odaiba show the bay’s mix of uses. Odaiba is known for the Rainbow Bridge, Fuji Television’s headquarters (designed by world renowned architect Kenzo Tange) and waterfront views back toward central Tokyo. Ariake hosts Tokyo Big Sight and the Ariake Arena, built for the 2020 Games. Together they give the bay a blend of homes, offices, sport, and leisure.
Tokyo Bay Area Map: Tokyo Metropolitan Government/Tokyo Updates 2022.01.31
What is the reclaimed land advantage?
Many of Tokyo’s reclaimed neighbourhoods were planned from a blank sheet, which gives them a particular character. Because the land started flat and empty, planners could lay out wide roads, leave generous space between buildings, and set aside room for parks. Districts like Toyomicho, Kachidoki, Tsukishima, and Tsukuda sit on land reclaimed from Tokyo Bay and were shaped with modern living in mind.
This means the street layout in these areas often feels more open than in older, organically grown parts of the city. The trade-off some buyers weigh is the question that comes up most with reclaimed land: how safe is the ground itself? The next section answers that directly.
How safe is building on reclaimed land?
The honest answer is that safety on reclaimed land depends heavily on two things: how the ground was treated, and how the building above it was engineered. Modern construction in these areas addresses both.
Foundation type is the first factor. When you build on reclaimed land, the way the foundation reaches solid ground matters a great deal. There are three main approaches.
| Foundation type | How it works | Relative safety |
|---|---|---|
| Type 1 – Direct contact | Piles pass through the reclaimed layer and reach the hard original ground below | The same standard as building on natural land |
| Type 2 – Pile-in-fill | Piles extend only into the reclaimed layer, used where reaching original ground is impractical | Less stable; can raise concerns |
| Type 3 – Through-fill | Piles pass through the fill into original ground material but do not reach bedrock | Safer than Type 2 |
The four reclaimed areas nearest the mainland, Toyomicho, Kachidoki, Tsukishima, and Tsukuda, sit closest to the original shoreline. Most properties there use Type 1 direct contact foundations, the strongest of the three.
Earthquake engineering is the second factor. Japanese towers use three main systems. Taishin (耐震) strengthens a building with reinforced walls, columns, and beams to resist shaking. Menshin (免震) separates the building from the ground using isolation devices set between the foundation and the structure. Seishin (制震) absorbs energy through dampers placed throughout the building, and it is the most common approach in Tokyo’s tower mansions.
Liquefaction is the question people ask about most, and Japanese engineering has a strong track record of managing it. The clearest evidence comes from the 2011 Great East Japan Earthquake: reclaimed land that had been improved beforehand, using methods such as sand compaction piles or gravel drains, came through the magnitude-9.0 earthquake without liquefaction damage. Tokyo Disneyland in Urayasu, built on treated ground, is a well-known example. Where damage did occur, it was concentrated in older fill placed after the mid-1960s and left untreated.
The encouraging takeaway is that newer, well-engineered developments on treated ground perform very differently from older, untreated fill. Buyers can also check the ground for themselves, as Tokyo publishes an official liquefaction risk map through the Metropolitan Government, so a property’s conditions can be reviewed area by area before any decision.
If the added space of bay-area living appeals to you, it helps to work with an agent who knows where to look. With over 25 years of experience in Tokyo’s property market, Housing Japan can point you toward buildings where the ground conditions, the foundation, and the home itself all line up.
What is being built next in Tokyo Bay?
Development in the bay’s reclaimed areas has not slowed. Harumi Flag continued to fill out as a residential district, and Toyosu added new visitor draws with Senkyaku Banrai in 2024. The larger story, though, sits further out in the bay.
The Tokyo Metropolitan Government’s Tokyo Bay eSG Project, announced in April 2021, covers about 1,000 hectares including the waterfront subcentre and the Central Breakwater reclamation area to the south. It aims to build a sustainable city for the next 50 to 100 years, with a first major target of 2030 for 5G networks, wind and floating solar power, and zero-emission transport, centred on hydrogen and renewable energy. An advantage the government points to is that the land it plans to use is largely empty, so work can start without disrupting existing residents.
This means the bay is likely to keep changing for decades, not years. For anyone looking at the area, the direction of travel is clear: more homes, more transport links, and more public space on land that, a century ago, was open water.
What should you consider before living in the bay area?
Living in a reclaimed bay district can suit people who value space, waterfront views, and good transport into central Tokyo. The area has become a popular choice for younger households, helped by newer buildings and well-planned streets.
Two practical points are worth checking for any specific property. The first is the ground: when the land was reclaimed, whether it was improved, and what foundation type the building uses. The second is the building’s earthquake system, since this varies from one tower to the next. These details are not always obvious from a listing, so it helps to ask. Housing Japan can confirm the construction year, foundation approach, and seismic system for properties across the bay area.
Frequently asked questions
Is it safe to buy property on reclaimed land in Tokyo?
Safety depends on the specific property. Newer towers on improved ground, using Type 1 direct contact foundations, or type 3 Through-fill foundations, and modern seismic systems, are built to the same standard as buildings on natural land. Older, untreated fill carries more liquefaction risk, which is why checking a property’s ground and foundation matters.
What does umetatechi mean?
Umetatechi (埋立地) is the Japanese word for reclaimed land, meaning ground created by filling in shallow sea or coastline. Tokyo Bay has been reclaimed this way since the Edo period, using soil, sand, and rock, to make flat land for harbours, industry, and, more recently, homes.
Which Tokyo neighbourhoods are built on reclaimed land?
Many of Tokyo’s bay districts sit on reclaimed land, including Toyosu, Harumi, Ariake, Odaiba, Shinonome, Tsukishima, Kachidoki, Toyomicho, and Tsukuda. Tsukiji, whose name literally means reclaimed land, was also created this way during the Edo period before the fish market moved to Toyosu in 2018.
Does reclaimed land liquefy in earthquakes?
It can, but treatment makes a large difference. In the 2011 earthquake, older untreated fill in parts of Tokyo Bay liquefied, while ground improved beforehand, such as at Tokyo Disneyland in Urayasu, did not. Modern developments use ground improvement and deep foundations to manage this risk.
Is reclaimed land still being developed in Tokyo Bay?
Yes. Harumi Flag and Toyosu continued to grow, and the Tokyo Metropolitan Government’s Tokyo Bay eSG Project, announced in 2021, plans a roughly 1,000-hectare sustainable district on reclaimed land, with major targets running from 2030 toward 2050 and beyond.
What Next?
At Housing Japan, we specialise in buying, selling, and managing residential luxury real estate in central Tokyo, including the bay area districts covered above. Whether you are a local resident or seeking a second home or temporary residence for business trips, we can help. Eith over 25 years of experience, Our one-stop service includes expert management, so everything is taken care of. If you would like to know the construction year, foundation type, or earthquake system of a specific bay-area property, get in touch and we will look into it for you.
