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.

Carrying a portable shrine on their shoulders, participants all clad in traditional happi coats, parade through precincts of the Kanda Myojin shrine during the annual summer festival in Tokyo, Saturday, May 9, 2015. (Photo by Eugene Hoshiko/AP Photo)

Dancers perform at the Harajuku Omotesando Super Yosakoi Dance festival in Shibuya, Tokyo on August 27, 2022. Super Yosakoi festival, is a two day festival that sees thousands of dancers, in hundreds of teams, energetically perform this unique Japanese dance style that combines traditional and more modern elements of movement and costume. (Photo by Damon Coulter/SOPA Images/Rex Features/Shutterstock)

Dog groomers participate in a contest at the “Interpets” international pet fair in Tokyo, Japan, 01 April 2021. (Photo by Franck Robichon/EPA/EFE)

Waka Tsukiyama and Sayaka Unagi compete during the Women's Pro-Wrestling “Stardom” at Korakuen Hall on September 06, 2021 in Tokyo, Japan. (Photo by Etsuo Hara/Getty Images)

A sommelier serves the glass with 2021 Beaujolais Nouveau wine of a young woman bathing in a red colored hot water bath, on the day of the Beaujolais Nouveau official release, at Hakone Kowakien Yunessun hot spring resort in Hakone, Japan, 18 November 2021. Japan is a major market for the Beaujolais Nouveau. However, the country's total Beaujolais Nouveau imports are expected to fall by 20 per cent from 2019 to around 3,6 million bottles, amid the ongoing coronavirus pandemic. (Photo by Franck Robichon/EPA/EFE)

A deer walks across a pedestrian crossing in Nara, Japan, Thursday, March 19, 2020. More than 1,000 deer roam free in the ancient capital city of Japan. Despite the town's tourism decline, these wild animals are doing just fine without treats from tourists, according to a deer protection group. (Photo by Jae C. Hong/AP Photo)