It is not because of the shape of the island that it has the nickname of “Rabbit Island” （ウ サ ギ 島, Usagishima）. The nickname of the island is due to the fact that it is overpopulated by these cute little animals. The island of Ōkunoshima was used in World War II to test chemicals that were used in combat, such as poison. They used rabbits to test the effects of the poison, but at the end of the war they were released by the workers. Today, rabbits roam the entire island, and it has become a tourist attraction.
Located an hour by boat from Hiroshima, Ōkunoshima is an attraction in which you can spend your holidays if you plan to travel to Japan. There is a hotel with hot springs, restaurant and a swimming pool. On the island you can visit a museum that tells about the history of Ōkunoshima and you can also visit the chemical factory.
Although today it is an attractive and friendly island, before it was very different. For 16 years in which it operated, the location of the island was omitted from the maps and kept the chemical factories secret. According to this article, the island produced five different types of gas, which were used in the war with China.
Being in Ōkunoshima you can enjoy the beach on the Seto Sea (the only beach in Japan with rabbits!). For children there is a museum full of activities. On the island there is also another museum a little more serious that talks about the history of the gas works, full of very interesting facts. However, the main attraction of the island is a lobby with a restaurant, cafeteria and a small shop with souvenirs. They also sell sandwiches for the rabbits for ￥ 100.
For more information about the tours and accommodation you can visit the official website of the Kyukamura National Park Resort Okunoshima. You will also find information about hotel rooms, food packages and other services.
To get to the island you must take a cable car from the Port of Tadanoumi (￥ 300 adults, ￥ 150 children. One way only) and then take a boat. They leave every half hour between 07:45 and 19:30. The port is a 5-minute walk from JR Tadanoumi Station, between Takehara and Mihara on the Kure Line (it takes 2 hours if you take a local railway from Hiroshima at a cost between ￥ 1280 and ￥ 1500).