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)

Japan Self-Defense Force members pay their respect to unidentified earthquake victims in vehicles during a mess funeral on April 8, 2011 in Yamamoto, Miyagi Prefecture, Japan. The 9.0 magnitude strong earthquake struck offshore on March 11 at 2:46pm local time, triggering a tsunami wave of up to ten metres which engulfed large parts of north-eastern Japan, and also damaging the Fukushima nuclear plant and threatening a nuclear catastrophe. The death toll continues to rise with numbers of dead and missing exceeding 20,000 in a tragedy not seen since World War II in Japan. (Photo by Athit Perawongmetha/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)

This photo taken on March 10, 2025 shows the former disaster prevention office building in Minamisanriku Town, Miyagi Prefecture, lit up on the eve of the 14th anniversary of the 2011 earthquake and tsunami disaster. (Photo by JIJI Press/AFP Photo)

A young woman wearing the summer Kimono, “Yukata” watches the goldfishes during the press preview of “Eco Edo Nihombashi Art Aquarium 2014” exhibition in Tokyo on July 10, 2014. The two-month-long goldfish exhibition will starts July 11. (Photo by Toshifumi Kitamura/AFP Photo)

Noriaki Iwashima gestures as he lies in a coffin to try it out during an end-of-life seminar held by Japan's largest retailer Aeon Co in Tokyo October 24, 2014. Funeral arrangements are normally left to those who have been left behind but the latest trend in Japan, which literally translates to “End of life” preparations, is for the ageing to prepare their own funerals and graves before they set off on their journey to the great beyond. With a population that is expected to shrink by nearly 30 million people over the next 50 years, the market for funerals, graves and anything related to the afterlife is still very much alive. (Photo by Toru Hanai/Reuters)