Takanoshima Island is a small land-tied island located in Fujimi, Tateyama City, Chiba Prefecture. It was once separated from the mainland, but the landscape changed dramatically as a result of the Great Kanto Earthquake of 1923, when the surrounding land was uplifted and a shallow area connecting the island to the mainland was formed.
Takanoshima lies immediately east of Okinoshima Island in Tateyama. Its unusual geological history, religious heritage, and wartime remains make it an interesting place for visitors exploring the history and landscapes of southern Chiba.
Takanoshima faces Tateyama Port and is located just east of Okinoshima. Before the Great Kanto Earthquake, it was separated from the mainland by the sea.
The earthquake, which struck in 1923, caused significant tectonic uplift along the coast. According to the Tateyama City History, the ground rose by approximately 2.1 meters at Takanoshima, about 2.4 meters at Okinoshima, and approximately 1.8 meters along the Tateyama coastline.
The uplift created a shallow tidal flat between Takanoshima and the mainland, gradually changing the island’s relationship with the surrounding land.
After the earthquake, the newly formed shallow waters attracted the attention of the Japanese Naval Air Force. In 1930, the surrounding area was reclaimed as part of a project to construct an airfield.
The reclamation eventually connected Takanoshima completely to the mainland. Today, the area forms part of the Japan Maritime Self-Defense Force Tateyama Air Base.
The landscape therefore reflects several stages of history: an offshore island, an earthquake-induced coastal transformation, a military reclamation project, and its present role as part of a Self-Defense Force facility.
Takanoshima has long been associated with the worship of Benzaiten, the island’s guardian deity. According to tradition, the shrine was established in 1092 through the efforts of Minamoto Chikamoto, who served as the provincial governor of Awa Province during the middle of the Heian period.
Benzaiten became an important focus of local faith, with prayers offered for good harvests, safety at sea, successful fishing, and prosperity in business.
The annual Benzaiten Grand Festival is held on May 14. The event was temporarily suspended during World War II but was revived in 1949 and has continued since then.
During the 1950s and 1960s, the celebrations were particularly elaborate. A Shio Festival was held on May 14, followed by an unveiling ceremony on May 15.
The Benzaiten shrine is currently maintained by Eisenji Temple, a Jodo Buddhist temple located in Numa, Tateyama City.
The continued care of the shrine reflects the enduring connection between Takanoshima and the religious traditions of the local community.
The island’s name has historically been written using two different forms: 高ノ島 and 鷹ノ島. The former was used originally, while the latter became more widely used from the Edo period onward.
Today, however, official topographic maps produced by the Geospatial Information Authority of Japan, as well as administrative documents, continue to use 高ノ島 (Takanoshima) as the official name.
Interestingly, a stone monument at the Benzaiten shrine is inscribed with the name “鷹之島辯天閣”. The same form of the name can also be found on religious amulets associated with the shrine.
Takanoshima also preserves the remains of the seaplane ramp used by the Tateyama Naval Air Force. This structure is one of the area’s wartime historical remains and provides evidence of the military role that the coastal area played during World War II.
After Japan surrendered in 1945, U.S. forces landed here on September 3. Direct military administration was carried out in the area for four days, making Takanoshima an important site in the history of Tateyama during the immediate postwar period.
Takanoshima offers visitors an unusual combination of geological history, religious heritage, and wartime history. The story of how the island became connected to the mainland provides a fascinating example of how earthquakes can permanently transform coastal landscapes.
Visitors can also learn about local faith through the Benzaiten shrine and explore the surviving traces of the area’s military past.
Takanoshima can be reached on foot or by bicycle from the Tateyama Port area. Parking areas and tourist facilities are available nearby, making the area relatively convenient to explore.
Takanoshima Island is a unique historical landscape where natural forces and human activity have shaped the same place over time. The uplift caused by the Great Kanto Earthquake, the subsequent naval reclamation project, the centuries-old worship of Benzaiten, and the surviving wartime remains all form part of its story.
For travelers interested in Japanese history, coastal landscapes, earthquakes, religious traditions, and wartime heritage, Takanoshima offers an opportunity to discover a lesser-known side of Tateyama and the southern Boso Peninsula.