Everyone who goes knows about the rabbits. Almost nobody who goes knows why there's nothing left on the island to stop them.
The ferry from Tadanoumi takes about fifteen minutes, and for most of it nothing happens. Then the boat rounds the headland, the small beach comes into view, and you notice the sand is moving.
It isn't sand. It's rabbits — dozens of them, then what looks like a hundred, already converging on the dock before anyone has stepped off, because they have run this calculation before and know exactly what a ferry means. You step onto Okunoshima and three of them are already standing on your shoe.
What nobody in your group mentions, as you dig through the bag of pellets you bought at the port kiosk, is that twenty metres behind you, past the gift shop, there is a roofless concrete shell with blackened walls — and the rabbits have never once gone near it.
Okunoshima is a small island in the Seto Inland Sea, administratively part of Takehara, Hiroshima Prefecture, reached by a short ferry from Tadanoumi Port on the mainland. It has one hotel — the national resort Kyukamura Okunoshima — a campsite, a nine-hole golf course, a beach, a small museum, and, by the Ministry of the Environment's last count, somewhere around five to six hundred wild rabbits with no natural predators to speak of. That last detail is the entire reason there are so many of them walking around a public beach acting like they own it. There are no permanent houses on the island and almost no shade, so most of a visit is spent being gently mobbed on open ground.
The lack of predators isn't an accident of nature. In the late 1920s the Imperial Japanese Army chose Okunoshima for a chemical weapons plant precisely because it was small, remote, and easy to seal off, and from 1929 to 1945 the facility produced an estimated several thousand tons of mustard gas, lewisite, and other agents — one of the largest such operations built anywhere before the war. Workers were sworn to secrecy so completely that some never told even their own parents what they did for a living, and every delivery, shipment, and worker moved through one tightly controlled dock.
The secrecy went further than silence. In 1938 the island was deliberately left off the Imperial Army's own survey maps of the Inland Sea — printed charts simply showed open water where Okunoshima should have been — and the handful of families who still lived there were relocated off it entirely. Hiroshima Prefecture's own tourism authority now markets the place, without irony, as "the island erased from the map." For roughly a decade, on paper, it didn't exist.
When the war ended, Japanese officials destroyed most of the factory's records before Allied forces arrived, and much of the plant itself was later demolished or left to collapse. What you can walk past today is a handful of roofless concrete shells — a former power station, storage bunkers, scorched brick — fenced off just enough to keep people from climbing into the parts that are structurally gone. A small Poison Gas Museum opened on the island in 1988, built and still partly informed by the testimony of surviving former workers: two plain rooms of photographs, gas masks, and production equipment, with a quietly damning timeline in Japanese and English.
The island's current fame has almost nothing to do with any of that. Rangers and the local museum say the wartime test rabbits were destroyed along with the plant when it was dismantled, and that today's population more likely descends from a handful of pet rabbits — perhaps eight — let loose on the island by visiting schoolchildren around 1971. With nothing around to hunt them, eight became hundreds within a few generations. That free ride has gotten shakier lately: a post-pandemic Environment Ministry survey found the population had nearly halved, from over a thousand down to five or six hundred, as fewer visitors meant less hand-fed food, and rangers have since reported wild boar and crows moving in to scavenge both leftover rabbit food and, on occasion, the rabbits themselves.
The story most visitors want to hear is the poetic one: lab rabbits that somehow survived humanity's worst instincts and were set free out of guilt, now living out their days on the beach where they were once tested on. It's a great story. It is also, by the museum's own account, probably not true — those wartime rabbits were killed off along with the factory, and the ones hopping around your ankles almost certainly descend from someone's unrelated classroom pets, dropped off decades later by kids who had never heard of mustard gas. The island didn't heal itself. Nobody atoned for anything. A completely unrelated, much smaller act — a school trip letting a few bunnies loose on a beach — happened to land on ground that had already been emptied of everything that could have stopped them. The chemical weapons and the rabbits aren't connected the way the internet wants them to be. They just happened, separately, to the same small patch of sand.
- The Imperial Japanese Army's plant on Okunoshima ran from 1929 to 1945 and is estimated to have produced several thousand tons of mustard gas, lewisite, and other chemical agents — among the largest such operations in the world before it was dismantled at the war's end.
- In 1938 the island was deliberately omitted from official Japanese Army survey maps of the Inland Sea; Hiroshima Prefecture's tourism authority still describes it today as "the island erased from the map."
- A Ministry of the Environment survey taken after the COVID-19 tourism slump found the wild rabbit population had nearly halved, from over a thousand to roughly five to six hundred, as fewer hand-fed visitors meant less food to go around.
Getting there
Take the JR Kure Line to Tadanoumi Station (around 90 minutes from Hiroshima Station with a transfer at Mihara); the ferry port is a seven-minute walk from the station exit. Ferries to Okunoshima take about fifteen minutes. Buy a bag of rabbit pellets at the port kiosk before boarding — nothing of the kind is sold on the island itself. A day trip is easy, but the island's one hotel, Kyukamura Okunoshima, also takes overnight guests if you want the beach without the ferry crowds.