When Rashomon won the Golden Lion at the Venice film festival in 1951, it opened up the floodgate forJapanese films to be shown in the west and made its director, Akira Kurosawa, who had already been making films for more than a decade, internationally known. It also launched the career of the film’s scriptwriter, Shinobu Hashimoto, who has died aged 100, helping him to become an essential component in the director’s celebrated oeuvre.

Hashimoto’s screenplay (co-written with Kurosawa), widely considered one of the best ever, was based on a 1922 short story, In a Grove, by Ryunosuke Akutagawa. Set in feudal Japan, it tells of a samurai travelling through the woods with his wife. She is raped by a bandit, who then kills her husband. At the trial, the incident is described in four conflicting, yet equally credible, versions by the bandit, the wife, the samurai (communicating through a medium) and a woodcutter, demonstrating the subjective nature of truth. This became known as the “Rashomon effect”, which plays with the viewers’ sense of perspective, making them question what they are seeing.

Rashomon, Hashimoto’s first screenplay, was the beginning of his long association (spread over 20 years) with Kurosawa. This covered the two categories into which most of Japanese film history was divided: jidai-geki, period samurai films, and gendai-geki, films in a contemporary setting. Among the jidai-geki to which Hashimoto made major contributions were Seven Samurai (1954), Throne of Blood (1957) and The Hidden Fortress (1958); and gendai-geki films such as Ikiru (Living, 1952), I Live in Fear (1955) and The Bad Sleep Well (1960).

Shinobu Hashimoto began writing while recovering from TB. Photograph: Kyodo

Many of them were co-written by Hideo Oguni, the process of which Hashimoto found challenging, frustrating, exhilarating and ultimately, gratifying. Kurosawa, himself a successful screenwriter who wrote about 30 scripts for other directors, enjoyed bouncing ideas off Hashimoto.

Kurosawa’s method was to get each writer to draft his own version of the same scene. The final screenplay would be a negotiated blending of the different versions. In his memoir, Compound Cinematics (2006), Hashimoto described the result as having the feel of a “mixed chorus”, adding that “collaborative screenplays don’t easily produce classics or masterpieces, but … thanks to passing under multiple pairs of eyes, holes don’t go unnoticed.”

Hashimoto was born and raised in the countryside in the Hyogo area of Honshu, Japan’s largest island. After being discharged from wartime service because of TB, he spent four years at a disabled veterans’ hospital. While recuperating he sent some of his first writing to the film director Mansaku Itami, who became his mentor. Hashimoto was 32 and working for a munitions company in Tokyo when the first draft of his screenplay for Rashomon made its way to Kurosawa. They agreed to meet and, according to Hashimoto, it took only a few minutes for Kurosawa to agree to make the film.

Like Rashomon, their next film together, Living, had a literary origin in that it was inspired by Tolstoy’s The Death of Ivan Ilyich, ingeniously transplanted from 19th-century Russia to 20th-century Japan. Discovering that he is in the terminal stages of cancer, an elderly civil servant spends his last months devoting himself to forcing through the building of a children’s playground in the slums.

Equally bleak, I Live in Fear was one of the writing team’s rare original (non-adapted) looks at modern Japanese society. It concerns a prosperous businessman who decides to emigrate to Brazil with his large family because he believes that the effects of a nuclear war will be less there. The family, wishing to remain in Japan and not lose a share of their father’s wealth, apply to the court to have him committed to an asylum.

Seven Samurai also had an original script for what is considered the greatest film in the jidai-geki genre. On a simple framework, Hashimoto, Oguni and Kurosawa constructed a superb narrative bursting with incident that is by turns exciting, absorbing, moving and amusing. In the same genre were The Hidden Fortress, a flamboyant samurai adventure, which George Lucas has acknowledged as an influence on the screenplay of Star Wars, and Throne of Blood, based on Macbeth, which revealed close parallels between feudal Japan and feudal Scotland.

Hashimoto’s work apart from Kurosawa included two solo written screenplays for Mikio Naruse, Summer Clouds (1958) and Whistle in My Heart (1959), subtle pessimistic melodramas a world away from Kurosawa. Perhaps Hashimoto’s best solo screenplay was for Masaki Kobayashi’s Harakiri (1962). The brutal tale is set at the end of the civil war in 1630, which left many samurai unemployed. One of them threatens ritual suicide if he is not taken on by a feudal lord. While remaining true to the traditions of the Japanese period film, Hashimoto managed to criticise the rigid codes of honour that are basic to their subject.

In addition, Hashimoto directed and wrote I Want to Be a Shellfish (1959), closer to Naruse than Kurosawa. The tragic tale tells of a meek barber in post second world war Japan who is unjustly tried as a war criminal for shooting a captive US soldier. On receiving the death penalty, he utters the film’s title, wishing he were a shellfish buried deep at the bottom of the ocean far from cruelty, poverty, war and torment.

It was over two decades before Hashimoto was given the opportunity to direct another film. Based on his three-decade record of success as a screenwriter, mainly on several of Kurosawa’s masterpieces, Hashimoto was given the chance by Toho, Japan’s leading film studio, to make Lake of Illusions (1982). It was a rather absurd melodrama and when it failed, Hashimoto retired permanently from the film business.

He is survived by two children, Aya and Shingo.

• Shinobu Hashimoto, screenwriter, born 18 April 1918; died 19 July 2018