OSAKA - An unexploded U.S.-made bomb believed to date from World War II has been discovered at a housing construction site in a residential district of Minoh, Osaka Prefecture, potentially requiring the evacuation of nearly 5,000 people during its disposal.
Minoh Mayor Ryo Harada announced details of the discovery at an emergency news conference at 11 a.m. on July 22, saying the bomb was unlikely to explode unless subjected to a substantial impact.
Construction workers found the bomb buried in the ground on July 17 at a site about 300 meters from Hankyu Minoh Station. The site, where a house is being built, was previously covered by a bamboo grove.
The cylindrical metal object measures about 1.8 meters long and 60 centimeters in diameter. It has been identified as a U.S.-made 2,000-pound general-purpose bomb, commonly known in Japan as a one-ton bomb, that is believed to have been dropped during the Pacific War.
The bomb weighs about one ton and is believed to contain approximately 500 kilograms of explosives. Its fuse remains attached, although authorities said there was no immediate danger of an explosion.
Members of the Ground Self-Defense Force inspected the bomb and covered it with a blast-resistant protective sheet as a safety measure. The bomb remains at the construction site, which is surrounded by detached homes and lies about a five-minute walk from Minoh Station.
The nearby road is used by local residents, schoolchildren and buses carrying kindergarten and nursery school children, adding to concern among people in the neighborhood.
"I had never heard of anything like this happening here, so I was surprised," one resident said. Another said the discovery was frightening because buses carrying young children regularly pass the site.
Unexploded wartime bombs continue to be discovered across Japan. In 2025, a bomb buried beside a taxiway at Miyazaki Airport exploded just one minute after an aircraft had passed nearby. No one was injured, but takeoffs and landings were suspended for an entire day.
A separate unexploded bomb was removed from a condominium construction site in Suita, Osaka Prefecture, in 2022. More than 900 households were temporarily evacuated, and JR train services were suspended during the operation.
Although Minoh was widely regarded as an evacuation destination during the war rather than a major bombing target, a similar bomb was found near the latest site about 50 years ago.
A resident who remembered the earlier discovery said local people were evacuated and train services were halted, creating widespread disruption and panic during the disposal operation.
The resident said he had never heard of the area suffering large-scale air raids similar to those in Osaka, but recalled being told that aircraft parts may have been manufactured or hidden nearby during the war.
Research by the Minoh City local history museum indicates that fighter planes may have been concealed in air-raid shelters in the city. Municipal authorities are continuing to investigate whether such wartime activity explains why the bombs were dropped in the area.
A disaster prevention and crisis management specialist said the one-ton bomb was larger than many unexploded bombs usually found in Japan. Its condition may have deteriorated over the decades, making it difficult to determine the exact risk of detonation.
The specialist said authorities must proceed with maximum caution because an explosion remains possible and noted that evacuating a densely populated central district would be a major undertaking.
Some residents may be reluctant or unable to leave their homes because unexploded bomb evacuations are rare, making advance notification and efforts to persuade residents to comply particularly important, the specialist said.
Minoh plans to erect a protective wall around the site before the Ground Self-Defense Force disposes of the bomb. No date has yet been set for the operation.
If authorities establish an evacuation zone with a radius of 300 meters, about 914 households and 1,770 people would be affected. The zone would include Minoh Station and an elementary school.
Expanding the evacuation area to the 500-meter radius recommended by the Self-Defense Forces would affect an estimated 2,594 households and about 4,930 people. An elementary school, nursery facilities and Hankyu Minoh Station are located within that area.
Rail services may have to be temporarily suspended on the day of the disposal operation, while restrictions could also be imposed on aircraft flying over the area.
The city said it would carefully coordinate the operation with the relevant authorities and promptly announce the disposal date and evacuation arrangements once they have been decided.
Source: KTV NEWS
