Matashichi Oishi, a victim of the 1954 U.S. hydrogen bomb test on Bikini Atoll in the Marshall Islands, has been crusading for a world free of atomic weapons and nuclear power plants.

But far from being driven by merely a hatred of nuclear weapons, Oishi’s motivation is also his “grudge” against what he sees as an injustice by the Japanese government over the controversial tests.

Oishi, 81, was just 20 when he and 22 other tuna fisherman on the Fukuryu Maru No. 5 (known as the Lucky Dragon) encountered a cloud of “death ashes” following an H-bomb test in the Pacific Ocean on March 1, 1954.

The 15-megaton explosion was equivalent to around 1,000 Hiroshima-size bombs.

“A flash of light hit us in the cabin, and I felt earthquake-like vibrations,” Oishi recalled during an interview at a mini-museum in Yumenoshima Park in Tokyo’s Koto Ward, where the 29-meter-long vessel is now housed.

After returning to the port of Yaizu, Shizuoka Prefecture, two weeks later, the crew were treated in Tokyo for burns, nausea and other health problems.

One crew member died six months later, while Oishi and the other surviving crew members were discharged in May 1955.

Over the years, many of his fellow crew members have developed liver dysfunction and other diseases, and 16 of them have passed away. Oishi has been affected by liver cancer and a cerebral hemorrhage.

Although the incident is viewed as the third atomic bombing disaster after Hiroshima and Nagasaki, the ship’s crew has not qualified for medical care benefits under a law intended to support atomic-bombing survivors.

Several months before their release from hospital, the incident was “politically settled” with a consolation payment from the U.S.

“The government is treating us in this way because they think little of fishermen,” Oishi said.

After feeling like a pariah in his hometown when he returned from hospital, Oishi relocated to Tokyo where he would run a laundry shop for 50 years until 2010.

Since then Oishi has become a torch bearer for the abolition of nuclear weapons.

In 2010, he visited New York to attend an international conference on the prevention of the spread of nuclear weapons, while in March last year he went to the Marshall Islands to attend a memorial service for Bikini H-bomb test victims.

Amid U.S.-Soviet nuclear rivalry, Washington carried out 67 nuclear detonations in the area from 1946 — less than a year after the atomic bombings of Hiroshima and Nagasaki — to 1958.

Speaking of Oishi’s dogged efforts, his eldest daughter Yoshiko Tanaka said: “A desire to send a message to as many people as possible is supporting him.”

When the Fukushima nuclear calamity started in March 2011, it came as a personal shock to Oishi because of his own experience of radiation exposure and an association he sees between the Bikini H-bomb test and Japan’s nuclear development.

The U.S. test took place at a time when Japan was starting to introduce nuclear power for electricity using enriched uranium provided by the U.S.

When it comes to the threat of devastation, Oishi argues, there is no difference between nuclear weapons and nuclear power plants.

“Although Bikini was a warning against that threat, it was ignored,” he said, condemning the Japanese government’s promotion of nuclear power.

At a protest rally held in Yaizu on March 1, Oishi reiterated his concern over the safety of nuclear plants.

“Unless the responsibility for the (Fukushima) nuclear accident is pursued and punishment is given, the same thing will happen again,” he said.