TOKYO (NYTIMES) - Japanese manga artist Takao Saito, who created Golgo 13, a manga comic book series that has sold in staggering numbers over a half-century, making its assassin-for-hire antihero one of Japan's most recognisable characters and the world of Japanese comics a darker, more adult place, died in Tokyo on Sept 24. He was 84.

His office said the cause was pancreatic cancer.

In tales of international intrigue and moral ambiguity, Saito's laconic but ruthless character Golgo 13, armed with a customised M-16 that almost never misses its mark, has appeared in movies, video games and even a self-improvement book that counselled businessmen to follow his single-minded commitment to his work.

In July, Golgo 13 became Japan's longest running comic series with the publication of its 201st collected volume, an event marked by Guinness World Records. The stories were originally published in weekly magazines.

Last month, the 202nd volume was published. About 300 million of the volumes have been sold, the series' publisher says.

With tales of sex and violence set against the backdrop of contemporary geopolitics, Golgo 13 marked a turning point for the manga industry, whose top creators had mostly made comics for children.

Saito became one of the foremost representatives of a new style of Japanese comics, known as "gekiga", or "dramatic pictures," which uses cinematic techniques such as close-ups and intercuts to tell the kinds of dark adult stories found in the work of film directors such as Akira Kurosawa.

He also drew attention for his innovative (now common) studio-based approach to making comics, one that effectively transformed the art form into an industry, with directors overseeing teams of writers and artists operating in assembly-line fashion to increase output and insure a homogenised style.

The gritty tales of Duke Togo, as Golgo 13 was also known, won fans across Japan, including the country's current minister of finance, Mr Taro Aso, who gleefully welcomed the news that a character seemingly drawn in his likeness had hired the assassin for a hit.

Without Saito's work, "we probably wouldn't live in a society where it's natural for adults to read comics", Mr Masahiro Kurata, a pop culture commentator in Japan, wrote in a tribute.

"And manga and anime probably never would have become representatives of Japanese culture," he added.

Takao Saito was born on Nov 3, 1936, in Wakayama prefecture, south of Osaka.

His father worked odd jobs and tried his hand at various artistic pursuits. His mother raised Saito and his four siblings, making extra money by rolling cigarettes at night.

Saito showed a talent for art from a young age, but it was a pursuit his mother strongly discouraged; as he recalled in an autobiography, she feared that he would turn out like his father.

After finishing middle school, he trained as a barber in Osaka and eventually opened a salon with his older sister in the city's red light district. The work did not suit him, however; he was afraid of razors.

He continued drawing on the side, painting movie signboards and selling pornographic drawings to members of the occupation forces stationed in Japan after World War II.

Those same GIs introduced him to American comics, including Batman and Superman. Movies, especially King Kong, were another major influence.

An early attempt at breaking into the comics industry went poorly: His submission to a boys' magazine was rejected by none other than Osamu Tezuka, Japan's most celebrated manga artist.

Tezuka, he said, told him that his themes and artwork were inappropriate for children.

The criticism only fuelled his ambition. By 1955, after two years of work, he published his first comic, the mystery adventure Baron Air.

Saito moved to Tokyo in 1957 and helped establish the short-lived Gekiga Studio, an artists collective dedicated to promoting a new style of comic book.

In a manifesto, the group rejected the term "manga", often translated as "whimsical pictures", as too soft for their vision of an art form that would tell compelling adult tales with a filmmaker's visual panache.

Saito quit the group to form his own studio, Saito Production, in 1960; there he created a variety of comics featuring heroes ranging from hard-boiled detectives to samurai.

One of his early projects was a licensed comic featuring James Bond, a spy with parallels to Golgo 13.

The factory-style production studio, modelled on those in the film industry, employed writers, artists and even researchers to ensure geographical and historical accuracy in Saito's stories. The system allowed him to churn out a constant stream of episodic adventures.

Saito said he approached the work strictly as a business, an attitude that set him apart from his contemporaries, who largely saw themselves as artists.

Golgo 13 was no different. The series, he said, was not an inspiration but a calculation intended to appeal to an audience hungry for drama and tales of violence.

The comic's name is a reference to Golgotha, the site of Christ's crucifixion. The character's calling card is a skeleton wearing a crown of thorns.

Saito had initially planned to end the series after 10 volumes, but it took on a life of its own.

Golgo 13 - a man from nowhere who has no origin story or moral code apart from delivering his lethal work on time and on budget - has been involved in nearly every major political event of the past half-century, including the Tiananmen Square incident in 1989; the death of Diana, princess of Wales, in 1997; and the American 2000 election recount.

Despite the series' enormous popularity, Saito had an ambivalent relationship with it.

In a 2016 interview with the tabloid newspaper Shukan Post, he said he much more preferred his work on a later series based on the experiences of the prostitutes whose hair he had styled in Osaka.

"It was the only work I ever drew because I wanted to draw it," he said of that series.

In contrast, his feelings toward Golgo 13 mirrored the assassin's attitude toward his own work: just a job, nothing personal.

After more than 50 years, the work had become an obligation.

He "belongs to the readers", Saito said, adding, "I can't just make my own decision to quit."

In the end, nothing could stop Golgo 13, not even his creator's death. The series will continue with Saito's blessing, the publisher said.