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.

People wrapped in blankets sit on the road as they are evacuated from a hotel after an earthquake in Kumamoto, southern Japan, in this photo taken by Kyodo April 14, 2016. A powerful earthquake with a magnitude of 6.5 knocked over buildings in southern Japan on Thursday evening, and police said people may be trapped underneath. (Photo by Reuters/Kyodo News)

Michiko Ohashi (C), wearing a costume decorated with snacks, performs with other members of pop group Pottya at a fan meeting celebrating her birthday in Tokyo, Japan, October 16, 2016. Competition is cutthroat among Japan's thousands of pop idol wannabes, but a unique concept is winning fame for a band of “chubby” girls deploying their cheeky cuteness to combat prejudices against obesity. (Photo by Kim Kyung-Hoon/Reuters)

Women in yukatas, or casual summer kimonos, take their selfie in front of paper lanterns during the annual Mitama Festival at the Yasukuni Shrine, where more than 2.4 million war dead are enshrined, in Tokyo, Japan July 13, 2017. (Photo by Kim Kyung-Hoon/Reuters)

Women in Kimono holding an umbrella walk on a street at Ginza shopping district in Tokyo, Japan, March 31, 2016. (Photo by Yuya Shino/Reuters)

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)

A member of the media has her photograph taken with an exhibit at Ghibli's Grand Warehouse during a media tour of the new Ghibli Park in Nagakute, Aichi prefecture on October 12, 2022. (Photo by Yuichi Yamazaki/AFP Photo)