Japan’s Lower Depths : THE GAMBLER’S TALE: A Life in Japan’s Underworld, <i> By Junichi Saga translated by John Bester illustrated by Susumu Saga (Kodansha International: $19.95; 253 pp.)</i>

We know the Japanese are hard-working to a fault. They trade unfairly. They live in tiny apartments and force their children to study for exams so difficult that, when some of them inevitably fail, they commit suicide--an option that many Japanese children consider seriously because, as we all know, suicide is a part of their culture.

The Japan we know is one of inane generalities.

Yet less than 1% of Americans can name any recent prime minister of Japan. And Japan’s history is even more obscure to us; we have hazy images of emperors and Commodore Perry, Pearl Harbor and Zero fighter planes, shoguns and Richard Chamberlain. (I remember my fourth-grade teacher in Pacific Palisades, who was considered locally an expert on Japan, showing our class a silk kimono and a picture book about Japan and telling us, literally, that Japanese people lived in houses made of paper.) Obviously, most of us are pitifully uniformed about Japan and, more important, the Japanese.

Junichi Saga’s first book, “Memories of Silk and Straw,” was a collection of personal accounts of life in a Japanese village at the turn of the century. Saga, a country doctor in rural Ibaraki Prefecture, transcribed conversations with his elderly patients throughout the 1970s. A fisherman, a midwife, a prostitute and a night-soil collector, among others, described their lives in their own voices. The result was a masterful depiction of old Japan and its people. Continuing in the oral tradition, his latest book is “The Gambler’s Tale,” the autobiography of a yakuza (gangster); the tale is rich with so many specific insights that the reader quickly forgets his preconceptions about Japan.

The gambler of the title, in a series of consultations with author Saga (who continues his practice to this day), tells of his privileged boyhood as a merchant’s son in rural Tsuchiura, of going on to run gaming houses and smuggling black-market pork into wartime Tokyo, of stabbing a man with a meat cleaver and of serving hard time in every type of lock-up in Japan. The yakuza speaks with a simple eloquence, well rendered in translation by John Bester, which reminds us that living history is an indispensable and reader-friendly means to understanding the past.

Saga slices the paper-house generalities as his yakuza describes beatings by the wardens of Sugamo Prison, a cold, stone building in northern Tokyo: “Police torture was an amateur affair, but in the jails it was really professional--in a different league altogether. I was wondering what they were going to beat me with, and it turned out to be a rubber hose, a six-foot length of the stuff. It really did the trick, too. It’s far more effective than hitting you with a hard stick . . . it bites into the flesh and snicks out a bit as it goes. . . . You feel it’s ripping out the marrow in your bones.”

Gradually, through precise and vivid description, a portrait of prewar Japan as a rural, cruel, hungry and isolated nation emerges. The gambler is awed the first time he sees a bunch of grapes or a muskmelon at the age of 25. He watches a policeman and a local citizen squabble over who is responsible for disposing the corpse of a man who has starved to death. He leads famished survivors of the 1923 earthquake as they scour the reeds on the Sumida riverbank for locusts to eat. (The ashes from that earthquake were used to fill in the many rivers that had once made Tokyo a canal city. And the houses were made of wood, not paper. Flimsy perhaps, but wooden.)

As the gambler discusses the privations and poverty that were the norm in Japan at that time, the realization sinks in that today’s Japan is only 50 years removed from a nation in which it was common practice in working-class neighborhoods to sell daughters or wives into prostitution in order to climb out of debt:

“Don’t get the idea that all the people living there were men: there were women, too. Whores, every one of them. . . . They couldn’t take time off just because they were a bit sick, or they’d got a temperature, or some skin trouble. Nobody helped them. So they went on selling their bodies till they rotted. . .” Saga occasionally interrupts his narrative with intrusive passages in italics, describing the gambler leaning forward in his chair, sipping tea or loading a pipe with tobacco. The device, of course, is intended to create the illusion that the gambler is delivering a monologue. But the gambler spins his yarn so smoothly--in chronological order and with a suspiciously accurate recollection of quotes and first and last names--that it reeks strongly of an authorial hand.

The gambler’s portrayal of himself and his fellow yakuza is in parts too self-exonerating and self-serving; he depicts protection and extortion rackets as friendly, semi-charitable benevolences. According to the gambler, the yakuza were virtually a nonprofit organization rather than the rapacious, greedy and murderous bunch they often were.

These are small faults. “The Gambler’s Tale,” along with “Memories of Silk and Straw,” is more enlightening as to the cultural heritage that makes up Japan than any Japanophile’s, journalist’s or scholar’s view. Saga and his gambler deal in specifics worth a thousand grade-school teacher--or even university professor--oversimplifications and generalizations.