Ken Watanabe’s latest film opens with an image of a polar bear resurfacing into the brilliant spring sunlight after months living underground. It’s tempting to see the scene as a metaphor for a career that has alternated between stretches of intense, highly acclaimed work and long periods of hibernation.

The 48-year-old was famously forced into semiretirement by a leukemia diagnosis in 1989, just two years after NHK’s samurai television series “Dokuganryu Masamune” launched him to fame. He fought the disease into remission, but it returned in 1994, leaving another five-year hole in his resume.

Watanabe is now re-emerging, blinking in the media spotlight after another year away from the cameras — this time self-imposed — following a string of high-profile Hollywood performances that have made him perhaps the best-known, most respected Asian actor on the planet.

In “The Last Samurai” (2003), “Memoirs of a Geisha” (2005) and “Letters from Iwo Jima” (2006), Watanabe brought charisma and depth to roles that in less capable hands were ripe for stereotype: a recalcitrant warrior in the dying days of feudal Japan; a middle-aged businessman in the runup to World War II; and the doomed Pacific War Gen. Tadamichi Kuribayashi.

In “The Last Samurai,” Watanabe’s rich, soulful turn in Edward Zwick’s Bushido sword-fest outshone one of Hollywood’s brightest stars, Tom Cruise, and earned him an Oscar nomination for best supporting actor. He is the heart and soul of “Letters from Iwo Jima,” a movie widely lauded as a masterpiece. Even his phoned-in performance in the exquisitely packaged but slight “Memoirs of a Geisha,” and a cameo in “Batman Returns,” were noted by critics.

All of which made his next career move appear odd. Watanabe returned to Japan to make “Ashita no Kioku (Memories of Tomorrow),” a low-key yet grueling, distinctly un-Hollywood drama about an office worker’s descent into Alzheimer’s disease. And though he briefly made the headlines again when he married actress Kaho Minami, since then public sightings have been so rare that you feel he might be in hibernation again.

But here he is: Tanned, fit and impeccably turned out in a tailored Italian suit for our interview in a central Tokyo hotel. Where has he been?

“How can I explain this?” says the 48-year-old Niigata native, struggling for words. “With ‘Letters from Iwo Jima,’ then ‘Memories of Tomorrow,’ I reached a sort of turning point in my acting. I had poured so much of myself into those movies that I really had no idea where to go from there. Of course I was offered scripts, but nothing that moved me at all in the same way. A lot of people advised me to go ahead and make a movie anyway. In the end I didn’t make one for nearly a year.”

But the time off seems to have done him the world of good.

“I said to my wife, ‘I’ve haven’t done anything in a year, I wonder if it’s OK?’ ” he recalls, smiling. “But she said ‘What are you talking about, you’re living your life.’ And it was a kind of relief to realize that this is what life is: spending time with your family and doing other normal things.”

The project that brings him back from hibernation is the BBC nature series “Planet Earth” (titled “Earth” in Japan) by documentary maker Alastair Fothergill, the creative force behind the huge worldwide hit “Deep Blue.” A filmic plea to rescue the planet from environmental destruction, “Earth” opens with a haunting shot of that polar bear coming out of hibernation and searching for footing on melting ice.

Watanabe, who narrates the movie’s Japanese version, recalls what he saw when he spent a month in the Arctic filming on a different project, before he got the call from the producers of “Earth.”

“The first dawn after winter up there is supposed to be mid-February, but the sun appeared to rise two weeks earlier. When I asked the locals about it, they said there have been huge changes here in the last few years. The weather is changing here too. So when I was asked to do the narration, I thought ‘I’ve got to do this. It’s so important.’ I mean, mankind has lived for such a short time on the planet, and maybe we don’t have much longer to go. But we can still help by doing even small things. Using water and electricity carefully, for example.”

It’s a long way from Hollywood, but Watanabe thinks the older he gets, the more inclined he is to seek out work that “says something” to the audience. Though he says that a return to the small screen is a possibility, he denies that stardom has turned him against the lure of Big Movies.

“Not at all,” he says. “It depends on the production. If the script is good, the cast and director good, I’ll go anywhere. You have to ask, ‘what is Hollywood today anyway’? I mean, there is a physical place by that name and a different aesthetic and scale, but movies are no longer made there. There is so much collaboration now. The money can come from Japan, the movie might have a Korean director and be made in the U.S.; it is not about where you make the movie anymore.”

The big difference he says is how much waste there is on a U.S. set. “They shoot a lot more and then select the best material. But once you get to the set there’s not much difference between a Japanese or foreign movie. There are directors who like to do a lot of takes, and there are others like (Clint) Eastwood (director of ‘Letters from Iwo Jima’) who usually say one will do.”

A smart, erudite man, Watanabe is acutely aware of the dangers of cultural typecasting inside the Hollywood machine. In the DVD voiceover for “The Last Samurai,” director Zwick explains that his star worked so hard because he “knew in some fundamental way” that the images of Japanese actors for decades were “two-dimensional at best and often caricatured.”

As great an actor as he is, he has made his name playing roles within the very restricted Hollywood template for Asian men: warriors, generals, businessmen and sinister oriental bad-guys. Is it possible to break out of this template?

“Well, I’d like to play ordinary people too, and I’m always developing such scripts (with my agent, advisers and friends).”

Still, he acknowledges it is difficult to find roles that don’t condescend. “About half the scripts sent to me feature characters I just can’t identify with, particularly one-dimensional businessmen or, if it’s a comedy, some absurd 10-year-old Japanese stereotype, some role related to IT or business . . . There’s no point in getting mad about it; it’s just the way things are. But I want to positively challenge such stereotypes.”

That sometimes means challenging the director and the script, he explains, even after accepting a role. “Oh yes, there are things in scripts that you cannot let go by. In ‘Letters from Iwo Jima,’ there were times when I told Eastwood, ‘This is just not believable,’ ” he says, adding that he made daily suggestions and asked the director to make sure that costumes, props and sets were accurate. “The story had to be true, but Eastwood is not someone I had to fight with because he always listened carefully and respected my opinions, right up to the end of the movie.”

He says the most serious script dispute on “Letters from Iwo Jima” was the death scene.

“We discussed it for weeks and I disagreed with the original version. Some people felt he should have committed seppuku, but I felt that beautified his death. Being the man he was, having asked so much of his men, he would have fought until he had erased himself. When nothing was left, he would have accepted death. I felt that very strongly.”

Watanabe’s essential seriousness is perhaps one reason why he dismisses the idea that he might be a sex symbol.

“I never understood that tag,” he says laughing. “I have no sense of myself as a sex symbol at all. But the meaning of sex symbol might be a little different in Japan to elsewhere. The Japanese version seems to come with a stronger emphasis on a sort of grownup or mature male charm. And if that’s the case, then I guess I’m happy to hear it.”

Watanabe always chooses scripts “on instinct” and claims it has rarely let him down. He says he immediately knew “Letters from Iwo Jima” and “Memories of Tomorrow” were special, but once he accepted the parts he had to dig deep into himself, a process he found exhausting. “I can’t become another person, no matter how much makeup I wear. Something of your own past, your experiences and personality always comes out in the role and that makes acting very risky. You’re exposed. You always wonder if you can pull it off.”

Acting outside of Japan is made harder by the language barrier, despite Watanabe having studied English intensely for “The Last Samurai” and “Memoirs of a Geisha.” He says dialogue itself is not so difficult, but understanding the meaning behind the words and what the director and the scriptwriter want is a challenge. The burden of playing Kuribayashi after his part as Katsumoto in “The Last Samurai,” two signature roles loaded with historical and political freight and scrutinized in Japan like few films before or since, added to his exhaustion last year.

Watanabe has admitted that he was “nervous” about making “Letters from Iwo Jima” — “a film that was so important to my culture.” Though he undoubtedly worked hard for his role, some critics didn’t appreciate the movie. “Doesn’t have much to say, except that Japanese are human beings too,” wrote the London-based Independent, ignoring what an achievement that was after decades of hoary cinematic cliches and banzai-screaming generals.

Watanabe rarely discusses his illness, though those who know him say his on-screen intensity and stillness is partly a product of being so close to death, and knowing it could come calling again. He admits to mining his memories of fighting leukemia when filming “Memories of Tomorrow.”

“I don’t think you should show those experiences on screen because they’ll take over the character you’re playing. But when I was making the movie, I began to remember. When you’re sick, you’re not thinking 24 hours a day about your suffering, about dying. You want to talk and laugh and think about other things. In the midst of trying to live your life normally, the fear and dread, the realization that it might all end, rises up inside of you. That’s what I brought to that movie, although I didn’t intend to at the start. The director was good enough to listen to me and we changed some scenes.”

The actor who blurs the boundary between screen roles and the guy in the shaving mirror is of course something of a cinematic cliche. Watanabe, who has built a career playing proud, honorable and fatalistic men, seems closer than most to his cinematic persona.

He is reputed to lead a frugal life, and has a reputation for being scrupulously careful and honest. There is something almost Buddha-like in his stillness and thoughtful, considered replies. So is he, as some of his press cuttings suggest, a modern-day samurai?

“Well, I’d like to live like a simple samurai’s life, with few possessions,” he laughs. “But in reality you start to accumulate things in your life. I try to differentiate between what I need and don’t need. I talk to my wife and children before buying things. But I think the samurai sensibility goes deeper: respect for others; using your time carefully; keeping promises. I think those are qualities that Japan used to have but that it is somehow forgetting. They’re important to me.”

“Earth” is released nationwide in Japan on Jan. 12.

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