Only after World War II did the secret spill: Ōkunoshima, located in the Inland Sea of Japan between Hiroshima and Shikoku, was the top-secret site for manufacturing chemical warfare. When the factories were closed down, a number of exotic wild rabbits were seen freely roaming the island. They were assumed to have been the test subjects for the chemical weapons, which the military failed to eradicate when the factory was demolished.

A woman looks at photographs of dogs to choose a pet to rent at Puppy The World on January 24, 2009 in Tokyo, Japan. Rent-a-dog is becoming increasingly popular amongst people who love dogs but are unable to look after a pet full time due to limited living space or long working hours. Customers pay the dog-rental outlet around 2500 yen (32.5 USD) for an hour, and usually take their rented pet for a walk along the nearby beach. (Photo by Junko Kimura/Getty Images)

A woman with Kimono looks at cherry trees in bloom in Shinjuku Gyoen in Tokyo, Japan on Thursday, April 4, 2024. (Photo by Noriko Hayashi for The Washington Post)

A child reacts as a family takes a break next to a cooling mist at the Sensoji temple as Japanese government issued heat stroke alerts in 39 of the country's 47 prefectures in Tokyo, Japan on July 22, 2024. (Photo by Issei Kato/Reuters)

This photo taken on March 10, 2025 shows the former disaster prevention office building in Minamisanriku Town, Miyagi Prefecture, lit up on the eve of the 14th anniversary of the 2011 earthquake and tsunami disaster. (Photo by JIJI Press/AFP Photo)

A model displays a creation from fashion brand Dairiku by designer Dairiku Okamoto for the 2022 Autumn/Winter collection at Tokyo Fashion Week in Tokyo on March 19, 2022. (Photo by Philip Fong/AFP Photo)

A Japanese woman and her daughter leave Daikichi kimono rental shop Wednesday, June 22, 2022, in Tokyo's Asakusa area famous for sightseeing, before attending their family friend's wedding. Japan is bracing for a return of tourists from abroad, as border controls to curb the spread of coronavirus infections are gradually loosened. Yusuke Otomo, who owns the kimono rental shop, can barely contain his excitement. (Photo by Hiro Komae/AP Photo)

A child in colorful kimono walks at Tokyo's Asakusa district on the occasion of Shichigosan celebration Thursday, October 22, 2020. The festival celebrates children aged three, five and seven for their well-being. (Photo by Eugene Hoshiko/AP Photo)