People watch the Pikachu parade which is a part of the 2023 Pokémon World Championships, at Grand Mall Park in Yokohama on August 11, 2023. (Photo by Philip Fong/AFP Photo)

A dog walks on the street as it snows in Kyoto on January 25, 2024. (Photo by Philip Fong/AFP Photo)

People are walking with umbrellas on a snow-covered street during the first snowfall of the year in Tokyo, Japan, on February 5, 2024. (Photo by Jerome Gilles/NurPhoto/Rex Features/Shutterstock)

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)

A bomb squad member wearing heavy equipment leaves the explosion site at the Yasukuni shrine precints in Tokyo, Japan, 23 November 2015. More than 100 police, firefighters and officials gathered at the site after an explosion was heard in the toilets of the Yasukuni Shrine, a controversial war shrine in the capital Tokyo. Local media reports said police found possible traces of an explosion, as well as batteries and wires at the shrine. There were no reports of injuries. (Photo by Franck Robichon/EPA)

People wrapped in blankets sit on the road as they are evacuated from a hotel after an earthquake in Kumamoto, southern Japan, in this photo taken by Kyodo April 14, 2016. A powerful earthquake with a magnitude of 6.5 knocked over buildings in southern Japan on Thursday evening, and police said people may be trapped underneath. (Photo by Reuters/Kyodo News)

Japan Self-Defense Force (JSDF) soldiers and firefighters make rescue works among mountain lodges, covered with volcanic ash near the peak of Mt. Ontake, which straddles Nagano and Gifu prefectures in this September 28, 2014 photo taken and released by Kyodo. More than 30 people were feared dead on Sunday near the peak of the Japanese volcano that erupted a day earlier, sending a huge cloud of ash and rock tumbling down its slopes, while packed with hikers. (Photo by Reuters/Kyodo News)

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.