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 competitor reacts as she emerges from the water during the Tough Guy event in Perton, central England, January 26, 2014. The annual Tough Guy race – “the toughest race in the world” – at Perton in Staffordshire. Tough Guy claims to be the world’s most demanding one-day survival ordeal. First staged in 1987, the Tough Guy Challenge has been widely described as one of the hardest races of it’s type with up to one-third of the starters failing to finish in a typical year. (Photo by Darren Staples/Reuters)

A foreign passenger wearing a protective suit poses as they prepare for their flight at Manila's International Airport, Philippines, Monday, January 18, 2021. Coronavirus infections in the Philippines have surged past 500,000 in a new bleak milestone with the government facing criticisms for failing to immediately launch a vaccination program amid a global scramble for COVID-19 vaccines. (Photo by Aaron Favila/AP Photo)

Bella Hadid and Gigi Hadid prepares backstage for Savage X Fenty Show Presented By Amazon Prime Video – Backstage at Barclays Center on September 10, 2019 in Brooklyn, New York. (Photo by Ilya S. Savenok/Getty Images for Savage X Fenty Show Presented by Amazon Prime Video)

Vanessa Hudgens attends Savage X Fenty Show Presented By Amazon Prime Video – Arrivals at Barclays Center on September 10, 2019 in Brooklyn, New York. (Photo by Dimitrios Kambouris/Getty Images for Savage X Fenty Show Presented by Amazon Prime Video)

American singer Dove Cameron poses with the "Video for Good" award for “Breakfast” at the 2023 MTV Video Music Awards at the Prudential Center in Newark, New Jersey, U.S., September 12, 2023. (Photo by Andrew Kelly/Reuters)

An image of the popular video game “Angry Birds” is displayed on an iPod Touch on March 18, 2011 in San Anselmo, California. The “Angry Birds” mobile device video game developer Rovio is begnning the process of seeking an initial public offering (IPO). (Photo Illustration by Justin Sullivan/Getty Images)