The light cruiser Nagara was an Imperial Japanese Navy warship that sank off Ushibuka, in the Amakusa Islands (Kumamoto Prefecture), after being torpedoed by a U.S. submarine during World War II. Of 583 crew, 348 were killed, and the wreck remains a powerful reminder of the tragedy of war.
Each year on August 7—the day she was sunk—a memorial service is held “to pay tribute to the spirits of the crew, and to convey to as many people as possible the horror of war and the value of peace.” In 2025, an additional offshore memorial service was conducted on August 9 as a milestone year marking 80 years since the end of the war.
My involvement began unexpectedly. While I was being interviewed during the underwater exploration of the Chousei Coal Mine, a journalist told me, “I am a descendant of one of the fallen from Nagara.” That encounter became the catalyst for me to research the ship seriously. Afterward, I began communicating with the people who organize the memorial service—Ushibuka Branch, Amakusa City Social Welfare Council—and with the bereaved families, and we started moving forward toward an underwater research.
Although Nagara’s sinking position has already been identified, the wreck lies at approximately 100 meters (and up to 120 meters on nautical charts) in open ocean conditions where currents are expected to be strong—making it an extremely difficult dive. DIVE Explorers (led by Yoshitaka Isaji) has continued exploration work in uncharted underwater caves and deep-water environments, and we intend to apply that experience to record the present condition of Nagara, while reporting progress on this page.
Nagara is one of the Nagara-class light cruisers, completed in 1922, and operated as an active frontline warship during the Pacific War. The class consisted of six ships: Nagara, Isuzu, Natori, Yura, Kinu, and Abukuma, collectively known—along with the Kuma-class and Sendai-class—as Japan’s “5,500-ton light cruisers.
A unique aspect of Nagara is that Inaba Shrine (Gifu City, Gifu Prefecture) was enshrined onboard as a shipboard shrine.
Principal particulars (as listed)
In July 1944, Nagara was engaged in the mission of transporting civilian evacuees from Okinawa to Kagoshima. She departed Naha on August 5, arrived at Kagoshima on August 6, and after disembarking evacuees, she was torpedoed by a U.S. submarine on August 7, 1944.
Nagara sank about 10 km offshore of Ushibuka, Amakusa City. Of 565 crew, 348 were killed, and 237 (or 235, depending on records) survived. It is also said that the survivors were rescued by local fishermen of Ushibuka.
At the time, the sinking of Nagara was strictly concealed as military information. During and even for some time after the war, memorial activities were rarely conducted.
However, Tsuru Sasaki (born 1898; died at 88) continued memorial activities for many years based on her personal conviction. In 1970, she used her own funds to build the Nagara Memorial Monument at a veterans’ cemetery on a hill overlooking the sinking site, and she is said to have prayed there every morning.
Her commitment was inherited by the Ushibuka Branch of the Amakusa City Social Welfare Council, and the memorial service has since become an annual event held each year on August 7. In 2025, as a special 80-year milestone, an offshore memorial service and ceremony were also held. In that offshore service, bereaved families and related parties boarded the Japan Maritime Self-Defense Force minesweeper Toyoshima, and approximately 150 people attended the subsequent ceremony.
As these memorial services were taking place, a journalist who had come to cover my underwater research told me, "I'm a family member of someone who died on the Nagara," and that was the beginning of my connection with Nagara.
As I listened to the people who have continued these memorial efforts and learned more through research and interviews, I increasingly felt the depth of their commitment to passing down Nagara’s story. I came to believe that actually diving the wreck—recording the present condition through photographs and documentation, and potentially recovering items—could become meaningful material that supports historical remembrance and inheritance.
I have conducted many wreck exploration, and each time I am reminded that a wreck is a “witness of history.” For that reason, I believe that a exploration should not be treated as mere underwater work: understanding the ship’s background, the people connected to it, and the history surrounding it is essential.
With that in mind, we arranged a visit to Ushibuka in December 2025 to meet the people working in Ushibuka Branch of the Amakusa City Social Welfare Council and to discuss not only what we might do, but also what we should not do—so that our efforts can truly assist those who have been carrying this history forward.
the Ushibuka Branch of the Amakusa City
On December 22, 2025, I (Yoshitaka Isaji) visited the Ushibuka Branch of the Amakusa City Social Welfare Council together with Jun Shimizu (my dive buddy for this project), Hirokazu Mori (a support diver and also my technical diving student), and the journalist (a family descendant) whose story prompted this project.
During the visit, we heard directly from those who have been responsible for memorial activities and for passing down the story. We were also told that documenting the current underwater condition and filming the wreck has been a long-held wish. With the 80-year milestone recently marked, the visit reaffirmed the value of creating records as “materials to pass down.”
The Social Welfare Council facility also includes the Nagara Memorial Museum, where many records and photographs are exhibited. A visitor comment notebook showed that people come from across Japan—evidence of the sustained efforts made over many years to preserve and share this history.
Following that, we were introduced to Diving Shop Tomikawa, which has supported the memorial service each year.
The owner, Mr. Tomikawa, runs the shop with his wife, and they also provide boats for bereaved families to board at memorial services. We asked for their cooperation in various areas as we conducted our research in Nagara, and they readily agreed.
We could not be more reassured by the cooperation of a local diving service that is familiar with the sea where we will be diving.
Diving Shop Tomikawa
Mr.Tomikawa and Us
The place where Tsuru Sasaki built the memorial monument is now known as the “Hill of Remembrance.” We were guided there and learned that the point directly below the monument—looking straight down toward the sea—is the sinking site of Nagara.
From the road to the monument is a climb of more than 120 steps, and we were told that Social Welfare Council staff also handle cleaning and maintenance. This ongoing care made a strong impression: remembrance here is not only an annual “event,” but also a daily act that continues throughout the year.
Related media coverage (About Dec 2025 Local Visit)
We are currently coordinating the exploration plan with the bereaved families and with the Amakusa City Social Welfare Council, which has conducted the memorial services. At present, considering periods when wind and current may be relatively weaker, we are discussing a neap-tide window in July 2026 as the first candidate. (The final date will be decided only if sea conditions and safety requirements can be met.)
The wreck lies in open ocean at approximately 100 meters (up to 120 meters on charts), where strong currents are expected—making this a highly demanding dive. However, the records obtained could support not only continued memorial activities, but also serve as valuable primary-source material that helps pass the memory of war to the next generation. With the goal of preserving the “present” of this history resting on the seafloor in a reliable form, we will proceed with careful preparation.
Affiliations may not be up to date.
Affiliations may not be up to date.
Copyright © 2024 Japan Karst & Underwater Exploration Project