With all its American, European and Asian cultural influences, it’s easy to forget that Japan is also an island nation in the Pacific.

Japan’s connection to another Pacific nation, the Marshall Islands, hit home to this writer one Sunday morning in the fish market at Misaki harbor on the Miura Peninsula in Kanagawa Prefecture, about an hour by train via Yokohama from Tokyo.

Women working there are fond of talking about husbands who spend a year on boats catching huge tuna off the Marshalls before returning with holds full of the frozen fish destined for the nation’s supermarkets and sushi bars.

Yet Japan’s connection to the Marshalls, an array of coral atolls in the central Pacific, is far deeper than that. For travelers, such as intrepid Japanese divers, the Marshall Islands are a glimpse of Japan’s past, when it saw itself as a Pacific archipelago isolated from the world. More importantly, the Marshall islanders, who suffered from U.S. atomic weapons testing after World War II, can teach Japan about the long-term effects of nuclear contamination.

Near the equator and International Date Line, the Marshalls should be a paradise, a perfect place to forget about nuclear reactors and mountainous tsunamis.

But Japan’s stamp is everywhere. The capital Majuro has a popular store named Momotaro, which is also a common surname among Marshallese. During my visit, I stayed for a while on remote Likiep Atoll with a lady named Yumiko and her husband Joe de Brum, who went to a pre-war Japanese school here in the 1930s and spent decades working on cargo ships going to and from Japan.

Alongside traditional outrigger canoes carved from the trunks of breadfruit trees, rusty ships — home to sailors from Misaki — catch tuna on hooks and lines for Japanese consumption. Sometimes they give it away free on the docks in Majuro, or sell it in Chinese-owned supermarkets for about ¥100 per hefty package.

Many Marshallese, who like instant-ramen noodles, eat sashimi the old-fashioned way by spearing a fish at night, tearing away the skin and gnawing it to the bone, washing it down with Kikkoman soy sauce. Their native language is rich with Japanese words, and they say they still feel an intimate connection to Japan, even as waves of Chinese move in from Taiwan, Hong Kong and the mainland.

More than a century ago, Japanese fishermen and traders ventured to the Marshalls when the island group was under German control. With a growing population as it rushed to industrialize, Japan was hungry for land and resources.

During World War I, Japanese troops (fighting on the winning side, as it turned out) occupied Enewetak and then Jaluit Atoll. Then, in 1920, the League of Nations approved Japan’s takeover of former German colonies (i.e. those of the loser) in the Pacific north of the equator. More than 1,000 Japanese were then resettled in the Marshalls, and even more in Palau and the Marianas, which now attract Japanese tourists, especially divers and golfers, who enjoy feeling at home while so far away.

Japan also brought in its education system, teaching de Brum and his generation to speak Japanese and respect Japanese culture.

“Japanese soldiers were tough, mean,” de Brum recalled at his beachside home on Likiep Atoll. “They didn’t go swimming or diving like Japanese do nowadays. They forced locals to give them copra, but they also snuck rice and soy sauce to us. They had a ‘house of hoodlums’, where guys would spend weekends with comfort women from Japan, then go home to Japanese wives waiting to give them fresh clothes.”

In the 1930s, Japan built air bases on many atolls, such as Kwajalein, that became targets for U.S. forces during the Pacific War. Historians estimate that half that island’s Japanese garrison of 5,000 people, and many Marshallese, died of starvation.

In one month in 1944, U.S. forces captured Kwajalein, Enewatak and Majuro, and eventually added all the Marshalls to what became the U.S. Trust Territory of the Pacific. De Brum got a job on Kwajalein, and learned to speak fluent English.

Even after Japan’s surrender in 1945, the war continued in the Marshalls in a different deadly form: U.S. testing of 67 atomic bombs from 1946 to 1958.

On March 1, 1954, in one test codenamed Castle Bravo, a hydrogen-bomb explosion with a power 1,000 times the combined explosive force of the Hiroshima and Nagasaki bombs spewed radioactive fallout over a much wider area than had been expected. The mushroom cloud roared up to 40 km into the sky and spread across an area 10 km in diameter, and fallout contaminated a huge swath of the ocean, and atolls in the Marshalls including Rongerik, Rongelap and its epicenter, Bikini. De Brum said the powdery white fallout on Likiep Atoll killed his three brothers and other relatives with premature cancer. “I was lucky,” he said. “I wasn’t on Likiep that day.”

In fact, he was a mechanic on his way to work on Kwajalein, about 450 km from the bomb site, when he saw a flash in the sky. “It was brighter, brighter, brighter. Like a flashlight in your eyes. I needed about 30 seconds to get my sight back. I thought it was the end of the world. Two or three minutes later, ja-rom. Rumble and banging. People fell down,” he recalled with excitement.

“They didn’t even tell us on Kwajalein to be ready. I was there when they brought that thing on the plane, with hundreds of military police to guard it. Nobody knew what it was.”

Reportedly more than 60 km east of the blast site on Bikini Atoll, Japanese tuna fishermen on the Daigo Fukuryu Maru (Lucky Dragon No. 5) saw a “sunrise in the West” and, eight minutes lates, a blasting sound. The crew said that fine white dust fell on them for three hours. As they scooped it into bags, the powder stuck to their hands and hair; they would later call it shi no hai (death ash).

Just as now in Japan with the ongoing nuclear crises at the Fukushima No. 1 nuclear power plant, reports back then about the Castle Bravo test (and others) were suffused with distortion, concealment and spin. When the 23 crewman returned two weeks later to port in Yaizu, Shizuoka Prefecture, they were reportedly suffering from headaches, nausea, burns, pains in the eyes and bleeding gums. Doctors diagnosed them with acute radiation syndrome and sent them to two Tokyo hospitals. The boat’s radioman, Aikichi Kuboyama, died seven months later at age 40 from acute radiation syndrome. In the media, his last words were reported to have been: “I pray that I am the last victim of an atomic or hydrogen bomb.”

Japanese scientists who studied fallout data disagreed with the official U.S. line at the time, which downplayed the impact of radiation, citing “national security.”

Others reported traces of radioactive materials reaching as far as India, Australia and Japan, and even to parts of the United States and Europe.

A U.S. magazine, Consumer Reports, warned of contamination of milk from an isotope that few people knew about — strontium-90. The U.S. Food and Drug Administration restricted imports of tuna. Japanese feared that radioactive tuna had entered the market. It was a lot like postdisaster Japan: year 2011.

Many Japanese were outraged that the U.S. was again harming Japanese. But the American and Japanese governments swiftly reached a deal giving compensation of ¥2 million to each fisherman — the equivalent of about $5,500 at that time. The governments also agreed not to grant the victims the same hibakusha (atom-bomb victim) status as survivors of the Hiroshima and Nagasaki bombings in August 1945, who thus become eligible for certain state entitlements.

The incident also inspired the creation of Japanese monster movies, including “Godzilla,” and it gave momentum to Japan’s anti-nuclear movement. Meanwhile, the tainted vessel still sits in a museum in Tokyo’s Koto Ward.

But neither the Lucky Dragon tragedy nor the “death ash” that rained down on many atolls in the Marshalls were enough to deter Japan from later following the postwar U.S. policy of “atoms for peace” — spreading a misplaced faith in “cheap, clean and safe” atomic energy around the world. Consequently, Japan would site more than 50 nuclear reactors on an archipelago as prone as almost anywhere in the world to earthquakes and tsunamis.

Marshall Islanders, meanwhile, had to deal with a fate that’s now befallen many in Fukushima Prefecture and beyond. Scientists reported that Bikini residents, who returned to their atoll after the tests, were later found with high levels of cesium in their bodies due to drinking coconut milk from tainted trees.

Within days of the incident, U.S. authorities set up what was termed the Castle Bravo Weapons Effects research section. This included under its Program 4 “Biomedical Effects” section what was termed Project 4.1 — titled: “Study of Response of Human Beings exposed to Significant Beta and Gamma Radiation due to Fall-out from High-Yield Weapons.”

Though highly secret at the time, this study found birth defects and thyroid cancer in children. The report said the Castle Bravo test exposed 239 Marshallese, and 28 Americans, to significant levels of radiation.

In 1956, the Atomic Energy Commission called the Marshalls “by far the most contaminated place in the world.” People worldwide avoided traveling there, and Marshallese carried a stigma with them wherever they went — sadly similar to what some Fukushima evacuees experience today.

From 1956 to 1998, the U.S. paid at least $759 million in compensation to Marshallese. Six decades later, nuclear claims are still ongoing — a harbinger of the long road ahead for Fukushima’s nuclear refugees having to deal with the nuclear plant’s operator, Tokyo Electric Power Co. (Tepco) and the government of Japan.

In 1997, the International Atomic Energy Agency declared Bikini was safe enough for walking and brief visits. But they estimated that living on the atoll and consuming local food would exceed 15 millisieverts per year. Though not declared safe for resettlement, Bikini was then opened to divers and sport fishermen. Dive magazines have named Bikini, with its “nuclear fleet” of sunken warships used as test targets, one of the top wreck-dive destinations in the world.

Many descendants of Bikini evacuees now live on remote Kili Atoll. Bikini’s city hall is a prominent building in Majuro, 850 km southeast of Bikini. Bikinians remain proud of their 2,000-year old heritage, and many hope to return to their ancestral homeland someday. But they still haven’t won sufficient funding to decontaminate their land.

Only 39 of the 167 islanders that were moved off Bikini in 1946 are still living, according towww.bikiniatoll.com. While some Bikini evacuees have made great strides, others have never fully recovered from the shock. Locals in Majuro say privately that too many Bikinians have succumbed to depression, diabetes, alcoholism and misuse of compensation funds. Drinking away their compensation packages and memories of their paradise lost, many are still trapped in the political and legal battles that have never ended in the Marshalls, and which are only now beginning in Japan.

These days, many Marshallese are more concerned about climate change and rising seas — a real and visible threat for people living on flat atolls at sea level with no high ground.

“The sea is too hot. The ice is melting. The water is rising. The coral dies, the fish die, the people die,” said Mentil Laik, a canoe-builder who speaks limited English. Asked why, he pointed to the sky. “Ozone,” he said. “Too many holes.”

The solution, he said, is also simple: “Stop pollution. Everybody.”

With no place to escape to, a natural disaster such as the tsunami that hit Samoa following a major earthquake there in 2009 could wipe the entire Marshallese nation of 60,000 people, and withe them 3,000 years of culture, off the surface of the Earth. “Some people say, in 2012, the water will come,” said Laik, making a wave motion with his hand. “Majuro, all gone.”

Yet he didn’t seem overly worried, because the Marshallese, like the Japanese, have a history of surviving almost anything. Raised on Ailuk Atoll, which suffered high radiation levels after the Castle Bravo test, Laik has dedicated his life to showing younger Marshallese how to build and sail traditional canoes, which have carried islanders on epic voyages for centuries — or maybe even millennia. In a worst-case scenario, he said his largest craft could sail “all the way to America.”

For many Marshallese, who have never been away from the roaring ocean, evidence of climate change is everywhere. Laik said the tide-line has been creeping up to the level of his boathouse in recent years. Taxi drivers talk about ancient trees on their home islands falling into the sea. Fishermen say they are catching fewer and smaller fish; while Japanese and Chinese vessels keep most of the tuna for sale back home.

Puddles of rain and sea water dot the landscape, causing bacterial infections in locals who saunter in flip-flops, unable to afford even cheap Chinese shoes.

“Our land is very low, so we are very vulnerable to changes in the environment,” said Morean Kabua, a hospital employee. “The weather has become very unpredictable. In the past few years, the rainy season has been going into December and January. Now it can rain anytime in Majuro.”

During Christmas 2008, a storm combined with unusually high tides flooded Majuro. Like a tsunami, the ocean poured across the land from east to west, blowing holes in homes, sweeping garbage into the lagoon, and terrifying residents on smaller islets such as Ejit, who dreaded being washed out to sea.

Locals and aid workers also worry that future storms could uproot Christian cemeteries perched dangerously beside the raging Pacific. “Graveyards are about to fall into the ocean,” said Ingrid Ahlgren, a Stanford University, California-educated anthropologist who was raised on Kwajalein. “There’s a potential that corpses can be exposed, and that’s a health risk. It’s going to become a bigger problem over the next 50 years.”

Many devout Christians still don’t believe the warnings about global warming, citing God’s promise to Noah that he wouldn’t flood the world again. “Many people believe that God will save them, and they don’t worry about it,” said Daisy Alik-Momotaro, director of Women United Together for the Marshall Islands. “They’ve been living on the same island their whole life, and they never show fear. So we have to convince these islanders that they have to save the world themselves. Eventually they realize that God is not happy, because we’ve been abusing the world.”

Fortunately, the Marshalls have normally remained outside the zone for typhoons that devastate Fiji, Tonga and the Philippines further west, and the ultimately Japan to the north. Many Marshallese believe the coral reefs would shelter them from tsunamis. Yet some researchers have estimated the Marshalls could become uninhabitable in 50 to 100 years — within the lifetime of children playing in puddles today.

“If that day comes, it will be a disaster,” Ahlgren said. The country only has two operational planes, she noted, and not enough boats to evacuate 60,000 people from hundreds of far-flung islands.

Ahlgren said that even if the entire population relocated to the United States, Japan or neighboring Micronesian islands with higher ground, the Marshallese government would have to find a new way to manage the tuna-fishing grounds, which Japanese and Chinese already exploit by paying small fees to the government.

“They are faced with the entire destruction of their culture,” she said. “Land is everything here. It’s where all the power exists. People are so connected to their land, they’re reluctant to ever leave it.”

Indeed, her words echo the feelings of many in Fukushima. “If you take away the land, the culture disappears. People are so afraid of this, they don’t even want to broach the subject in public.”