I knew I'd been typecast when I came back from a vacation to find "Tokyo Vice: An American Reporter on the Police Beat in Japan" (Pantheon, 352 pages, $26) on my desk, with a note from the newspaper's books editor suggesting that I might want to review it.

I've been a Japan-ophile for the past 40 years or so. I followed my curiosity to a bachelor's degree in religious studies, largely focusing on Buddhism. I've studied Japanese martial arts for many years. And I've been a reporter with an investigative bent and an interest in organized crime for decades. I suppose it was a reasonable suggestion.

But I wondered: Who would really want to read some hack's war stories about how he went to Japan to study Zen and karate, only to abandon that path to became a cops reporter?

I put the book aside, figuring I'd get to it, if at all, when I had nothing else to read.

Don't make that mistake.

When I finally picked up "Tokyo Vice," author Jake Adelstein hooked me with the first paragraph in the prelude, "Ten Thousand Cigarettes": "Either erase the story, or we'll erase you. And maybe your family. But we'll do them first, so you learn your lesson before you die."

What follows that threat (from an organized-crime enforcer) is an improbable journey that led Adelstein to a 12-year stint with Yomiuri Shimbun -- a Japanese-language daily newspaper, circulation 13.8 million -- and a showdown with Japanese organized crime groups known as Yakuza.

These aren't the two-dimensional Yakuza popular in movies and anime. Adelstein portrays them as a blend of the sociopathic killers of "Pulp Fiction," the honor-bound mafioso of "The Godfather" and the ruthless corporate raiders in the movie "Wall Street."

What makes "Tokyo Vice" so utterly readable is Adelstein's self-deprecating humor and his stark honesty about his own peccadillos and at least one possibly catastrophic judgment error. I won't spoil the book by explaining further, but suffice it to say that he crossed a number of ethical lines that would have gotten him suspended or possibly fired from a U.S. newspaper, and he will always wonder whether his inexperience or carelessness led to the disappearance of one of his sources.

Adelstein revealed his offhanded humor in a Nov. 16 appearance on Jon Stewart's "The Daily Show." Talking about his relationship to a Yakuza kingpin who'd threatened to kill him a couple of times, Adelstein said, "It's like a battered marriage between me and this guy."

Reacting to audience cackles, he asked, "Is that inappropriate?"

"Your sense of scale may be off," Stewart quipped.

But behind the humor and pure entertainment value of "Tokyo Vice" lies a thought-provoking tale of the roles played by outlaws, law enforcement and the journalists and other professionals who try to walk the line between them.

"I hope there's something universal in the contents beyond just making people aware of cultural differences between the United States and Japan, or reiterating the importance and value of investigative journalism," Adelstein says in promotional materials. "Maybe the real lesson is to be kind and helpful to the people you care about whenever you can, because it's good for them, and good for you, and your time with them may be much shorter than you imagined."

It's a message that comes through like a temple bell.

Dan Browning • 612-673-4493