Ōkunoshima is a small island located in the Inland Sea of Japan between Hiroshima and Shikoku. During World War II the island used to be a top-secret military site manufacturing poison gas for chemical warfare. Today, it’s completely overrun with cute, fluffy bunnies who are the island’s main inhabitants.

Between 1929 and 1945, Okunoshima Island was a chemical warfare production site for the Imperial Japanese Army that produced over six kilotons of mustard gas. The island was chosen for its isolation, conducive to security, and because it was far enough from Tokyo and other areas in case of disaster. The program was shrouded in secrecy and during its 16 years of operation, Okunoshima was even erased from maps. Residents and potential employees were not told what the plant was manufacturing and everything was kept secret.

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With the end of the war, documents concerning the plant were burned and Allied Occupation Forces disposed of the gas either by dumping, burning, or burying it, and people were told to be silent about the project.

According to some sources, the rabbits were brought to Okunoshima to test the effects of the poison and released by workers when World War II ended. Others sources claim that a group of schoolchildren were on a field trip, when they released eight rabbits in 1971. Regardless, the original bunnies of Okunoshima and their successive generations of offspring thrived in their predator-free environment.

Today the 700-square-meter 700,000 square-meter island is home to more than 300 rabbits that roam freely, earning the nickname of Usagi Shima, or Rabbit Island. Though wild, the rabbits on the island are used to humans and will approach visitors in search of a snack, and hop on to laps. Visitors are allowed to pet and feed the animals, but in an effort to preserve the bunny population, dogs and cats are not allowed on the island. Pellets of rabbit food are sold for ¥100 a cup at the Kyukamura Okunoshima resort hotel located on the island. The hotel has recently seen a steep increase in visitors to the island since knowledge of the island’s furry residents spread on the Internet.

Although most visitors to the island come here to see the bunnies, Rabbit Island’s poison gas legacy isn’t over. Okunoshima is also home to the Poison Gas Museum opened in 1988, in order to alert as many people as possible to the dreadful truths about poison gas.

Some argue the island might not be completely safe as there has never been any major decontamination of the whole island. It’s rumoured that there are several sealed locations on the island where workers reportedly buried gas when the war ended.

Also see: Tashirojima - The Cat Island of Japan and The Swimming Pigs of Big Major Cay, Bahamas

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The Poison Gas Museum. Photo credit

Former poison gas laboratory on Okunoshima. Photo credit

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Sources: Wikipedia, Coilhouse, Gethiroshima, CNN, MNN, via Oddity Central