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)

Men ride on a “mikoshi” or portable shrine as local people carry it into the sea during a festival to wish peace in the ocean and good fortune in the new year in Oiso, west of Tokyo, January 1, 2015. (Photo by Yuya Shino/Reuters)

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)

A rickshaw man runs under the blooming cherry blossoms in Tokyo, Sunday, March 29, 2015. (Photo by Shizuo Kambayashi/AP Photo)

An employee of Daikin Industries Ltd works the production line of outdoor air conditioning units at the company's Kusatsu factory in Shiga prefecture, western Japan March 20, 2015. As Japan heads into the season of peak demand for room air-conditioners, Daikin managers have been tasked with figuring out how to boost output by some 20 percent at the 45-year-old Kusatsu plant that six years ago the company had almost given up on as unprofitable. (Photo by Yuya Shino/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)

Japanese ornamental dolls (hina dolls) are displayed on the stone steps at Tomisaki shrine during the Katsuura Big Hinamatsuri festival in Katsuura city of Chiba prefecture on February 28, 2023. (Photo by Yuichi Yamazaki/AFP Photo)