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 applies lipstick in a car that is parked at a beach facing a volcanic rock called Devil's Finger outside Yuzhno-Kurilsk, the main settlement on the Southern Kurile island of Kunashir September 15, 2015. Russian residents of the island chain at the centre of a dispute between Japan and Russia that has held up a treaty to formally end World War Two hope a diplomatic solution will lure tourists and investment to help refurbish rickety infrastructure. The Southern Kuriles are referred to in Japan as the Northern Territories. (Photo by Thomas Peter/Reuters)

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)

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 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)

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)