The fallout from the explosion created a blizzard of radioactive ash that covered an area of the ocean far larger than anticipated, which exposed the crew members of the ' Lucky Dragon No. 5 '—a Japanese tuna fishing boat—to lethal levels of radiation. The crew of the Lucky Dragon returned to port covered in burns and poisoned with an acute radiation sickness that would claim the life of one of the fishermen a few months later. Homage is paid to both events in the opening scene of the original Godzilla, which features a small fishing boat on a quiet sea, the tranquility of the image shattered with a blinding explosion that consumes the screaming fishermen. With the horrific images from the Lucky Dragon still fresh in the minds of Japanese audiences, early screenings of the original Godzilla were reportedly "watched in somber silence, broken by periodic weeping."

The Godzilla franchise began in 1954 under the auspices of the Japanese director Ishirō Honda, just a decade after the United States dropped nuclear bombs on Hiroshima and Nagasaki. Godzilla was originally conceived as a metaphor for nuclear war and just months before the film's release, the United States tested a massive nuclear device near Bikini Atoll in the Pacific Ocean that ended up being nearly two times more powerful than expected.

The king of monsters has saved and decimated Japan anew in each of the dozens of remakes that have appeared over the years, but the one thing that has remained constant over the monster's storied history is its uncompromising politics. Nowhere is this more apparent than in Godzilla vs the Smog Monster, a 1971 experimental cautionary film about the environment that nearly ruined the series.

Godzilla is, and always has been, a radical. For over 60 years, the 300-foot tall antihero has towered over the Tokyo skyline as a perennial warning of the folly of nuclear war and unrestrained technological advancement, like some kind of giant reptilian Jane Fonda.

Also known as Godzilla vs Hedorah, the film was the 11th Godzilla movie to be produced by Toho studios, and by far its most unorthodox. Banno had cut his teeth working as an assistant director to the legendary Japanese film director, Akira Kurosawa, and Hedorah was his directorial debut at Toho Studios. But despite Banno's lucky break, his work, on Godzilla vs Hedorah nearly ended his career before it started.

"Godzilla was being aimed more at children with things like Godzilla dancing, and the audience had been shrinking," Yoshimitsu Banno, the film's director, told SciFi Japan shortly before his death. "So for the 11th Godzilla movie I wanted to include a message about pollution for adults to enjoy, too."

It wasn't until the release of Godzilla vs the Smog Monster in 1971 that Japan's favorite reptilian monster truly returned to its radical roots.

Considering its somber themes, Godzilla was an amazing success in Japan. The film single-handedly created an entire genre— kaiju—that focuses on the misadventures of (usually) giant monsters. In 1955, Toho studios made Godzilla Raids Again, but the franchise didn't really hit its stride until the 1960s, which saw a new Godzilla film released almost every year. Honda directed most of these releases and presided over Godzilla's transition from a horrific metaphor to a more playful, entertaining antihero.

"When Godzilla was first released, it was really intended as a political statement," William Tsutsui, the president of Hendrix College and a renowned Japanologist, told me over the phone. "Today we're used to Godzilla as sort of kiddie fare, but the director saw this as a meaningful statement on nuclear war and the threat of technology to the natural environment."

As it gains strength Hedorah moves from the ocean to land, before finally learning to fly, instantly killing anyone with Sulfuric acid as it passes overhead. (In one scene, a group of school girls collapses as the smog monster flies over the school, a not-so-subtle reference to a real life incident that had happened in Japan involving a group of school children who collapsed from exposure to toxic smog).

News of the attack quickly prompts a panic in Japan and newscasters issue safety warnings urging citizens to stay vigilant, especially those in polluted industrial cities. Amid the panic, Yano attempts to understand the biochemistry of Hedorah, which he describes as "entirely different from any other form of life." As Yano discovers, Hedorah is a product of industrial pollution that grows stronger by feeding on the smog emitted by factories and vehicles.

Made in just 35 days with half the budget of previous films in the franchise, Godzilla vs Hedorah tells the story of the scientist Dr. Toru Yano and his son, Ken, who discover a toxic microorganism living in the ocean off Japan's coast. As Yano discovers, this seemingly innocuous piece of sentient sludge has the ability to self-replicate and tiny pieces of the stuff are able to morph together into a larger organism. In an attempt to learn more about the creature, Yano goes scuba diving where he has an encounter with Hedorah that leaves severe burns all over his face and body.

"When he showed the finished film to the long time producer of the series, Tomoyuki Tanaka, Tanaka told Banno that he had ruined Godzilla," Tsutsui told me. "Which is hilarious because by 1971 there wasn't much artistic quality left in the series to ruin."

In many ways, Godzilla vs Hedorah is exactly what you'd expect from the franchise: there are lots of shots of grown men wrestling in monster costumes, gratuitous laser battles, and all the (mostly) intentional comedy that results from the combination of giant monsters and low budget filmmaking. But Banno's take on the classic monster is also unique, both thematically and stylistically.

By trapping Hedorah between two electrodes, Yano and the Japanese military are able to zap the sentient smog until it is turned to dust and rendered impotent. In one of the strangest and unintentionally comic film endings of all time, Godzilla chases after a small part of the smog monster that has escaped by using his laser breath to fly through the air. When he finally has the smog monster defeated, he punches into its chest and rips out what is presumably the monster's cold, polluted heart.

As Yano desperately tries to discover a way to defeat Hedorah with science, Godzilla emerges from the water and takes matters into his own hands. But even the smog monster is too much of a match for the King of Monsters and Godzilla keeps succumbing to its toxic foe. Just when all appears to be lost, Yano discovers a way to defeat Hedorah, which essentially amounts to [SPOILER ALERT] creating a giant battery.

"Godzilla movies are generally pretty sterilized for their youth audiences," Tsutsui said. "There's not a whole lot of actual violence and you never see people dying. In Godzilla vs Hedorah you do. It really underlined the threat of pollution in a very emphatic way."

The film is set against a backdrop of 1970s Japan, which like America had seen its share of flower children, and all the hedonism and naive optimism the hippies brought with them.

"There was an environmental movement gaining steam in Japan in the early 1970s," Tsutsui said. "There was a sort of California-style protest and hippie psychedelic fringe to the movement, but in Japan environmentalism really had more of the feel of a citizen's movement that became a huge civic issue."

Nevertheless, half of the film takes place in a Japanese rock club, where Yano's older son grapples with psychedelic hallucinations as Hedorah takes over the city. The smog monster eventually makes its way into the club and ends the party prematurely, at which point the elder Yano and his fellow students decide to take action by organizing a "million man march" against the smog monster.

Despite their good intentions, the students' march is woefully under-attended and devolves into yet another dance party. Banno's satire has a clear target and message—the impotence of well-intentioned environmentalists who naively believe that they can reverse the damage of industrial pollution with enough marches and bonfires.

The psychedelic influence of the times also makes itself felt through the film's structural elements, which feature a number of trippy and bizarre animated sequences. One of these scenes simply cycles through pictures of celestial objects like nebulas and galaxies while a voiceover ponders the infinite and another features two women walking in gas masks.

"Banno was an incredibly creative guy and I give him huge credit for that," Tsutsui said. "To the extent that there is an indie Godzilla movie, Hedorah is it."

Ultimately, however, the film was a reaction by Banno against the smog and industrial pollution he saw contaminating cities like Yokkaichi, where residents were known to contract "Yokkaichi asthma" from constantly breathing in the thick smog.

Shortly before Banno started filming Godzilla vs. Hedorah in 1970, Japan hosted the World Expo in Osaka. The Expo featured a pavilion that, as the New York Times described it, "emphasized the practical use of modern technology" by showing a vision of a future city whose residents lived in harmony with nature and one another. As part of this exhibition, Banno had assisted Tomoyuki Tanaka, the Toho Studios producer behind the Godzilla franchise, in creating the pavilion's many visual elements, but was distraught by the gulf between the vision of the future in the pavilion and the reality of Japanese life.

"At the Expo we created the pavilion showing off all these new technologies that were supposed to lead to a bright future, but in reality the situation was much worse than reported by the Club of Rome think tank and others at the time," Banno said in the interview with SciFi Japan. "All the waste from these factories had created a terrible situation. We had no idea how far the pollution problem would go with all this self-made unstoppable slime."

In 1970, Japan was grappling with the reality of its pollution problem, which could be seen in thick clouds of black smog blanketing cities and the industrial chemicals pumped into the ocean that had created a "Sea of Death" in the Dokai Bay of northern Japan, which lost all traces of aquatic life as it was polluted with untreated industrial wastewater. As the high cost of these polluting activities began to manifest itself in the failing health of Japan's citizens and widespread protests, the government took drastic action to curb its pollution problem. In what became known as the Pollution Diet (the Diet is the national legislative body in Japan), the Japanese government passed 14 laws in quick succession that took a hardline approach to curbing industrial pollution.

The laws enacted during the special pollution Diet were radical even by today's standards. Lawmakers abandoned a clause in the previous Basic Pollution Control Law that required pollution regulations to be in harmony with the economy, out of concern that citizens would see this as favoring the economy over the environment. They introduced national pollution control mechanisms that superseded local standards and placed strict regulations on the industrial sector that prohibited the contamination of public water supplies and the air.

"Within one or two years all the smoke went from black to white because the market for desulfurization equipment expanded very quickly," Banno recalled in 2014. "It was said Japan had overcome the pollution problem, but the pollution of the ocean with PCB and plastics still continues to this day."

Earlier this summer, Yoshimitsu Banno passed away at age 86 in Kawasaki, Japan. The uncompromising director had harbored ambitions for a sequel to Godzilla vs Hedorah up until the very end, and a few years ago there were rumors that the smog monster would be rehabilitated for a Hollywood remake. Although Banno's dream never materialized before his death, he did play a major role in bringing the terror of Tokyo back to the big screen in the 2014 Hollywood blockbuster, Godzilla, by brokering the deal between Toho Studios and Legendary Pictures.

Although the country is not without its environmental problems, today Japanese cities are among the least polluted in the world. This is due in part to the swift action against industrial pollution orchestrated by its government nearly 50 years ago, and was reinforced by Banno's unique take on a Japanese icon in Godzilla vs Hedorah. For all its corniness and pulpy action sequences, at the film's core is a radical message that still resonates with modern audiences: the only way to take meaningful action against climate change is to stomp out the main problem—complacency.