TOKYO -- Mayumi Kato uses hers to send photos of herself to her boyfriend -- several times a day. Masato Kozu keeps his handy in case he spots a celebrity. And feline-lover Itari Obata enjoys snapping cats on the street.
Mobile phones with built-in digital cameras are taking Japan by storm and, amid a proliferation of new uses, bolstering Japan's reputation as the most advanced and creative cell-phone market in the world. It is a phenomenon likely to be repeated in the United States, where picture phones are just starting to appear in advertisements.
"This year's boom in Japan will spread next year to Korea, China and beyond," said Masahiko Ishino, an analyst at Mitsubishi Securities. "This is no passing fad. It's something that will be around for a long time."
Among the attractions of the phones are their simplicity of use and sleek, compact size. A couple of clicks allow you to take a photo, store it or send it as a standard e-mail attachment. You can personalize the photos with written messages, which can be received by virtually any mobile phone in Japan, with or without a camera, or any ordinary e-mail anywhere in the world.
"It makes taking pictures easy since you've always got your mobile phone with you," says Kiyonori Agake, a 36-year-old unemployed salesman. "I never seem to have a camera on me when I need it."
Finding new uses for the pictures has become something of a treasure hunt here. Buyers at Tokyo's world famous Tsukiji fish market's auction beam shots of $15,000 frozen tuna to sushi chefs across Japan before placing their bids. The Osaka police now get dozens of cell-phone photos a month from concerned citizens of crime scenes, stolen cars and suspects. And video microscope firm Scalar Corp. offers free attachments so customers can send skin and scalp photographs to beauty centers for an automated analysis.
Perhaps inevitably, the new technology has been tapped for matters of the heart.
People are using the pictures as digital alibis, sending previously taken shots of themselves at work to a husband or wife back home, when in reality they're off having an affair.
"One problem is making sure you're wearing the same clothes when you get home that you wore in the picture," says Atsushi Baba, a systems engineer.
Matchmakers have embraced the technology as "singles wanted" Web sites proliferate, allowing people to study cell-phone photos online before deciding to take the next step. Magazine articles help the self-conscious with tips on how to look your best in a thumbnail frame.
"You can't use matchmaking sites these days without Sha-mail," said Takenori Kobayashi, a 20-year-old university student, referring to J-Phone Inc.'s service, the market leader. "If you're a girl looking for a boy, or vice versa, you've got to have it."
Then there is the seamier side. Japan's active voyeur world is also using them to take pictures of people without their knowledge, given how small and easy to hide the handsets are.
Hundreds of Web sites with names like "Sneaky Shot Mania" and "Erotic Kingdom" have sprung up, plastered with hazy, out-of-focus shots of lovers in parks, women's legs, schoolgirls on subways.
"Many people steal shots in the trains or under the stairs, which is why I've held off buying one," Agake says. "If you're a guy, you could take a shot, there's a misunderstanding and suddenly you find yourself arrested."
Aware of the potential for abuse, carriers have equipped all models with a loud ring -- and no "off" switch -- that blares whenever a photo is taken.
J-Phone's Sha-mail service has been something of a godsend for this perennial also-ran in Japan's mobile-phone wars. "To be honest, I never dreamed it would be so successful," said Keiji Takao, the company's deputy general manager of technology. Two years ago, J-Phone was lagging behind competitors NTT Corp. and KDDI and badly in need of an edge. Takao, sometimes called Mr. Sha-mail, remembered seeing a survey on what teenage girls kept in their purses, namely a mobile phone, a music player and, frequently, a disposable camera.
With rivals already going after the mobile-tunes market, he proposed they meld cell phones and cameras. This wasn't brain surgery, but earlier attempts using bulky attachments and oversized phones had failed, and J-Phone's timing was fortuitous. Digital cameras were dropping in price and size, and electronics manufacturer Sharp was eager to get into the market. After an internal debate, the company pushed ahead.
After a modest launch in late 2000, J-Phone's volume built steadily until, by the end of last year, 10,000 users a day were signing up. "That's when we realized we had a big hit," said Makoto Iwabayashi, J-Phone's advertising manager.