'Rabbit island' a dark outpost of Japan's chemical warfare

Strict secrecy

Okunoshima, located in Takehara, Hiroshima prefecture, covers just 0.7 square kilometers.

Records show that the Imperial Japanese Army began building a poison gas factory on Okunoshima in 1927. From the start of production in 1929 until Japan's defeat in 1945, more than 6,000 people worked there.

Shizuyo Yamauchi, head of the Poison Gas Island Historical Research Institute, said former workers recalled toxic substances settling near the ground during production.

"It looked like a blanket of white fog around their feet," she said.

Production was kept under strict secrecy. Okunoshima was guarded around the clock, while trains running along the opposite coast were required to cover windows facing the island. Okunoshima was even removed from maps.

Yamauchi said poison gas produced on the island was later used on the battlefield and took many lives.

"Starting a war is an act of aggression, and aggression itself means inflicting harm on others," she said.

After Japan's defeat, large quantities of related documents were burned, although remnants of wartime facilities, including poison gas storage sites, can still be found across the island today.

With much of the wartime records destroyed, efforts to preserve this history have relied largely on island residents. It was not until 1988 that local peace activists established the Okunoshima Poison Gas Museum, collecting historical materials and raising funds themselves.

Its exhibits now include equipment used to produce chemical agents, remnants of chemical weapons, protective clothing and gas masks, as well as documents related to orders by the Imperial Japanese Army to use poison gas in China.

The museum also has a section on chemical weapons abandoned in China, documenting cases in which munitions left behind by the Imperial Japanese Army were unearthed during construction and other activities decades after the war, causing injuries.

The exhibit calls on Japan to properly dispose of these weapons and compensate the victims.

Masayuki Yamauchi, director of the Poison Gas Island Historical Research Institute and a former high school teacher in Hiroshima prefecture, has long researched Japan's chemical warfare. He said the issue of chemical weapons abandoned in China was not added to the museum's exhibits until 2011, after local citizens urged the authorities to include it.

He also expressed concern about the museum's future, warning that changes in the political climate could eventually put it at risk of closure.