Fanatical followers of Japanese comic books and cartoon animations have become an economic force in Japan. These so-called otaku are spending more than $2 billion a year on their obsessions, as Catherine Makino reports from Tokyo.

Otaku are obsessive fans of comic books, called manga, and cartoon animations, called anime. Japan's biggest-selling manga comic, "Shonen Jump," sells millions of copies each week.

In Tokyo's Akihabara district, packs of otaku in their 20s and 30s spend hours in nondescript buildings shopping for anime, comics, DVDs, games and action figurines. Akihabara also holds major events such as the Comic Market, a twice-yearly event where more than a quarter of a million otaku come to buy and sell self-published comic books.

Sandra Shoji is an instructor of humanities at Toyo Gakuen, a Tokyo university, and has studied the otaku phenomenon.

"They represent the new recreational majority among young people," she says. "They're very much into anime, or animated films, they're inspired by comic books, and they seem to have problems watching anything over the length of about 15 minutes."

According to the Nomura Research Institute, there are about 2.4 million otaku in Japan. Once a fringe group, they have now entered the economic mainstream, spending $2.5 billion a year on comics, animated films, computer games, action figurines and other products.

They can also be found at cafes in Akihabara that cater especially to them. On weekends, some men stand in line for up to two hours for a table at establishments like Cos-cha.

Cos-cha is one of the so-called "maid cafes," where waitresses dress in scanty black maid's outfits with white aprons, black net stockings and lacy white headbands. They greet male customers with "Welcome home, master."

When Hiroyuki Ito, a first year student at Yokohama University, sat down at Cos-cha recently, the waitress dropped to her knees and looked up to take his order. The costumes and behavior were inspired by a French maid character in an erotic comic book.

Ito says much of his life is spent in this fantasy world of cafes and comic books.

"I spend about five hours a day watching anime and reading my favorite comic books," he says. "I also draw my own fantasy stories, like women wizards who are super heroes."

Sandra Shoji said most otaku use this fantasy as an escape from the pressures of real life.

"They see that is it is very creative, and that they can enter a world where anything is possible," she says, "unlike the real world, where they basically have no job future, where they're told exactly what to do in school, or by their mothers. This is something where they can completely escape and find their own world."

The appeal of otaku has spread to women since the success of romantic anime movies such as last year's "Train Man," in which a typical 23-year-old otaku man wins the love of a beautiful woman.

Women otaku now have their own version of maid cafes. Last March, one called Swallowtail opened on a narrow street in Ikebukuro, a Tokyo shopping district. Waiters dressed as elegant butlers in black tailcoats greet the mostly female customers with, "Welcome, home, Madame."

In contrast with the cheap-looking maid cafes, Swallowtail looks like an English manor, with custom-made furniture and chandeliers hanging from the ceiling. It averages more than a hundred customers a day, ranging in age from 20s to 40s.

Shoji says the culture has now spread outside the otaku cafes.

"I went to a bakery, and all the women were dressed in their black-and-white maid costumes. I went to a family restaurant for women with children, and all the waitresses were in their maid uniforms. And the woman manager was in her butler uniform," she says.

A "princess restaurant" has opened in Ginza, an expensive district in Tokyo. Young women are greeted by waitresses in pink maid costumes, escorted to a throne chair and given the royal treatment. In some Ikebukuro hair salons, women are given hairdos by men dressed as butlers.

Sociologists in Japan say the otaku culture caters to the needs of people, especially Japanese men, who are not able to relate to human beings on a deep level, and may lack communication skills.

Those who study the otaku trend say the phenomenon will not disappear anytime soon. And they note it is not only for Japanese anymore. Devout fans of anime can be found all over the world, as Japanese-style cartoons and related toys and games show up in magazines in dozens of countries.