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.

Dancers dressed as futuristic characters perform during a show at The Robot Restaurant on June 29, 2014 in Tokyo, Japan. The now famous Robot Restaurant opened two years ago in Kabukicho area of Shinjuku at an estimated cost of 10 million U.S. dollars. Performances are held three times a day and cater mostly to foreign tourists. The cabaret style shows include bikini clad futuristic dancers, performers dressed as robots and a host of large scale robots and vehicles controlled with remotes by stage hands dressed as Ninjas. (Photo by Chris McGrath/Getty Images)

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)

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)

Participants with traditional Japanese tattoos (Irezumi), related to the Yakuza, walk through the Asakusa district during the annual Sanja Matsuri festival in Tokyo on May 20, 2018. Sanja Matsuri festival is a celebration for the three founders of Sensoji Temple in the Asakusa neighbourhood with nearly two million people visiting during the three-day event. (Photo by Behrouz Mehri/AFP Photo)