Masayuki Yamamoto, 34, is up all night, bent over his work in a cramped one-room flat. Sleep will come during the day, on his couch. Meals arrive in plastic containers from a nearby convenience store.

His passion: drawing manga, the Japanese-style comic books that are soon to be in a store near you.

For this, Yamamoto gave up a regular 9-to-5 office job as a graphic artist. "Life was easier when I was a salaryman," says Yamamoto, "but it's so fulfilling to draw manga."

Manga comics are Japan-born, but their success as an export is growing. Their hallmarks are simple lines, big-eyed characters and a TV-like sequence of panning, close-ups and breathless dialogue that moves incrementally, frame by frame. Unlike American comics, manga comics are read by children and adults throughout Japan; on trains, at home, at work, at school.

The genre was noted for its violence and sex, and Yamamoto admits he resisted pursuing a career drawing the comics because manga artists had a dark image of otaka -- night-dwelling misfits obsessed with comics, computers or video games. Academic theses have been written about what the impossibly long-legged, big-breasted women and well-muscled men in manga say about the Japanese self-image.

But manga is shedding its dark past and coming out of the closet. Its precursors already have invaded America. Saturday morning TV cartoons in the United States already feature lots of anime -- the Japanese shorthand for animation in the manga style. The Pokemon (Japlish for "pocket monster") boom started with a manga comic derived from a video game. Powerpuff Girls, an American derivative, has captivated the preschool set.

Hollywood movie studios are planning to make new movies out of three manga: "Dragon Ball," a space adventure; "Akira," an anime classic on motorcycle toughs in post-apocalypse Tokyo; and "Astro Boy," the original Japanese robotic superhero.

Buoyed by acceptance of the plot and characters, two Japanese publishers plan to bring the real thing -- the comic magazines themselves -- to the United States later this year.

"The American market is ready to accept our manga," says Nobuhiko Horie, president of Coamix. Shueisha publishing house and the San Francisco-based Viz Communications will begin publishing an English version of Japan's top comic magazine, Shonen Jump, as a monthly in November. Coamix is planning to publish a weekly magazine called Raijin Comics, also in November.

Horie is confident enough in the U.S. venture that his and other comics will be published to be read in the Japanese direction -- from right to left, back to front. The language will be changed, but the plot and drawings will be the same as the Japanese editions. And they will be drawn in Japan by manga artists like Yamamoto.

There is no shortage of aspiring artists for the work. Despite manga's vaguely dark background, thousands of fans fancy themselves creators, and some, like Yamamoto, are willing to pay high dues to prove it. Yamamoto sent his comic strips to magazines in vain for three years, running up $5,000 in credit card debt to pay his living expenses.

"It was tough," he says. But a four-page manga was finally published two years ago in Young Magazine, a weekly. Since then, he's been making money -- about $2,500 a month after he pays two assistants to draw backgrounds. His second comic book has just been published by a major publishing house. He's moved up to a bigger one-room apartment and now has a girlfriend who respects his job.

Yukako Takemura, 39, lives with her parents in central Toyama prefecture and willingly endures marathon three-day, 16-hour-a-day sessions at the home of another professional to draw manga background characters -- the "mob." She makes $250 for those three days, but she is not complaining.

"It's not bad for my level," she says, "and it's educational and fun."

Ever since Takemura drew manga of big-eyed princesses when she was 9 years old, drawing manga has been her passion. She drew manga for a game magazine for a while, but her life as a professional cartoonist didn't last long. Still, she continues to draw manga for a small number of fans. "I have a dream to make a living by manga," she says.

Like Takemura, some aspiring artists endure long years of apprenticeship. Manga is such a risky career that many draw it as a hobby, publishing their works for private fans or on the Internet. But those who want to become professionals may break into the business by winning a new cartoonist's award or winning over a magazine's editors.

The dream of skyrocketing success as the next Pokemon fuels them. In Japan, if a manga story becomes popular, it often becomes a weekly TV show or a movie. Readers of the manga volumes -- many are like books, two inches thick -- spend $4 billion on 1.5 billion copies of these publications each year. That amounts to more than one-third the total spent for all the books and magazines published in Japan. Recently, manga publishers have joined with television and video game makers to launch multimedia products, rather than wait for spinoffs.

Manga comics are the source of 20 to 30 percent of TV dramas, according to Yoshihiro Yonezawa, a manga critic. Parents no longer cringe when their kids read the comics; if fact, they often lament that children favor video games over reading manga.

As young readers brought up on manga became adults, the themes of their comics changed. There are now manga on topics as diverse as the corporate world, war and finance. Yamamoto's specialty is a manga strip about friends who restore old cars.

Manga enthusiasts gather at places like the Comic Market, held in August in Tokyo. Every six months, the city's big convention center is crowded like a train station during rush hour. On row after row of tables, amateur cartoonists sell their homemade manga booklets. Visitors stroll through, stuffing big bags with their favorites. Some get into the spirit by dressing up like popular characters such as Sailor Moon or the pirates of "One Piece," now Japan's hottest manga.

The first time Japan tried to bring manga to the United States, in the 1970s, it failed. But the comics quietly spread to Asia and Europe. Horie said for American readers, he will have to tone down some sexual and violent expressions. He also wants to cultivate American manga artists. For now, South Korean, Taiwanese and Chinese cartoonists are rising, but they haven't reached the level of the Japanese yet, experts say.

But the opportunity is there for anyone, says Naoto Yasunaga, an editor of Young Magazine. "As long as your manga is fun," he says, "it doesn't matter which nationality or tribe you're from."

Fans of manga comics often are inspired to make their own drawings. Shigeyuki Sekine's sold at the Tokyo Comic Market.At Tokyo's Comic Market, manga's fans display their homemade work, like Naomi Kobayashi's comic, at left, for sale. Masayuki Yamamoto, top, gave up an office job to become a manga artist.