On Feb. 21, 1996, Akiko Koyama, the actress wife of renowned film director Nagisa Oshima, received a phone call at her home in Kugenuma Kaigan, Kanagawa Prefecture. It was from an official at the Japanese Embassy in London.

“Is this the home of director Nagisa Oshima? … Mr. Oshima has had a stroke.”

Koyama, who was in the kitchen preparing lunch, collapsed in shock.

Oshima was on a lecture tour sponsored by the Japan Foundation. He had arrived in London the previous day, given a talk, and was in a taxi on his way to Heathrow Airport to catch a flight to Belfast.

The events surrounding that stroke, which has latterly left Oshima reliant on a wheelchair, form only a part of the moving account of an exceedingly fond marriage.

In “Onna toshite, Joyū toshite” (“As a Woman, as an Actor”), published in December 2011 by Seiryu Shuppan, Koyama tells the intimate story of a relationship marked by mutual respect, deep love and an unending devotion.

But it wasn’t a relationship that was easy to achieve — are they ever? — given the obstacles thrown up by the insults of commerce and the exigent demands of physical affliction.

Koyama, born in 1935 as the fifth child — and only daughter -in a well-to-do family, was discovered at an early age by Kiyoshi Takamura, then head of Shochiku’s Ofuna Studios. Takamura was also responsible for starting the career of one of Japan’s greatest stars, Keiko Kishi.

Although Koyama’s straight-laced father was up in arms at her move into acting, she debuted in 1955 and soon rose to star status herself. In fact, over the following three decades she appeared in nearly 90 films and countless television shows and plays.

It was on the set of her second movie that she met Oshima, who was then a young assistant director. When she came home late from the shoot, she found her father standing at the front door like a fierce guardian deity, hollering, “What are you trying to do, kill your father? !”

It was taboo in those days for an assistant director to so much as make eyes at an actress. That, though, wouldn’t be the last time this iconoclastic director was to break a taboo.

As for Oshima and Koyama, their work inevitably caused them to experience long separations; and it wasn’t until five years and 360 letters later that they married.

After that, the couple’s first crisis arrived in 1960. In three groundbreaking movies, Oshima had by then established himself as the leader of the new wave of Japanese cinema. Four days after the release of his fourth film, “Nihon no Yoru to Kiri” (“Night and Fog in Japan”), the leader of the Japan Socialist Party, Inejiro Asanuma, was assassinated by a 17-year-old rightwinger while giving a televised speech. Shochiku Co. Ltd. — Japan’s leading film and theater company — immediately withdrew the film, which is about young leftists opposing the Treaty of Mutual Cooperation and Security between Japan and the United States that was signed in January 1960.

Oshima did not take this lying down. He quit. Koyama’s career, too, was damaged by this move of conscience. To make matters worse, they had just bought land on which to build a home near Shochiku’s studios outside Tokyo.

Afterward, Koyama said to her husband: “I wasn’t able to become a very good actor, but I have the confidence to be a good wife.”

Oshima protested.

“You continue acting until the public tells you they’ve had enough.”

What followed was several years of dire personal struggle on both their parts to forge careers independent of the major studios. Nonetheless, during the turbulent 1960s Oshima was able — with money saved up by Koyama from her acting career, and funds lent by friends — to make some of the emblematic films of his generation. But even as late as 1968 and ’69, he was shooting his masterpieces, “Kōshikei” (“Death by Hanging”) and “Shōnen” (“The Boy”) on a shoestring.

The shoot for “Shōnen” took a year, and called for the cast, starring Koyama, to travel the length of Japan. As Koyama herself has told me, there were times during the making of that film in which they ran out of money to do the next week’s scenes. At such times, she would model in kimono for local products and appear in commercials in provincial cities to keep the production on track.

When Oshima was charged with obscenity in connection with the script of his rare and beautiful film about the extremes of love, “Ai no Corrida” (“In the Realm of the Senses”), Koyama’s support did not waver, despite the fact that their elder son, Takeshi, a middle-school student at the time, was being heckled by some classmates with the likes of “Your old man makes dirty pictures!”

Oshima eventually won the case; but as he told me in 1981: “In a society like Japan’s, you’re guilty the minute someone accuses you.”

The second half of Koyama’s book “As a Woman, as an Actor” deals with the sheer trials of survival. Oshima recovered quickly, if incompletely, from the stroke — so much so that he often appeared on talk shows and was able to shoot another feature film. But health setbacks followed, requiring virtual around-the-clock care.

This put a colossal burden on his wife’s shoulders, all the more so when she slipped into a state of clinical depression that lasted four years and at times necessitated hospitalization.

“No matter how hard I tried, it was no good. I felt as if my heart had been branded with the words, ‘Bad Wife,’ ” Koyama writes.

It was a trip the couple took in 2000 to Cannes, where they had spent such glorious times in the past, that jolted her out of her misery. She saw the adulation offered Oshima for his lifetime achievements and felt an immense pride. Now, upon reading this book full of honest pathos and expressions of devotion, I am reminded of the abiding contribution its author has made to the achievements of her husband and the Japanese film industry in general.

There are moments of profound affection and ones of equally profound desperation described here. Oshima’s illness has robbed this once magnificently articulate man of speech. It has taken a bitter toll on Koyama’s health as well.

“I want to live valuing each and every day as it comes,” she writes. “That has been my motto ever since the day that my husband, Nagisa Oshima, fell ill in 1996 — and it hasn’t changed. Faced with my husband’s illness, I made it a priority to care for him over pursuing my career as an actress. And I have not wavered once from that choice.

“I consider the family unit to be that of husband and wife. I always told my children, from when they were little, that they were my precious treasures, but that the person I loved more than anyone was their father.”

Akiko Koyama made a brave choice that not all wives or husbands, faced with the same trials, would have. But as the title of the book suggests — and as its contents reveal — she has not, in actuality, sacrificed any part of herself for another.

This is the message that comes out so clearly from this book: that our life is defined by the ways we nurture, cherish and express the love we are able to find in it.