Takeshi says that he pays ¥6 300 (R530) a month to NTT DoCoMo for unlimited Internet access, allowing him to download adult movies on his cellphone.
"A mobile is far handier than a computer for internet access," he says, declining to give his surname. "I seldom use a PC outside the office."
Takeshi and other pornography fans are feeding a surge in demand for movie downloads in Japan, home to the world's first third-generation (3G) wireless network.
Continues Below↓While profiting from the traffic, DoCoMo and KDDI say they have been forced to impose limits on the heaviest users as the $74 billion (R592bn) network feels the strain.
"When you have unlimited data, you're going to have an issue with capacity - it's an issue that's been waiting to happen," says Windsor Holden, the principal analyst at Juniper Research.
"It wouldn't surprise me that it happens in Japan first because they've had 3G for so much longer."
Softbank, the third-largest network and the Japanese operator of Apple's iPhone service, says it is also considering restrictions on users with unlimited data plans.
While telecoms companies say privacy laws prevent them from seeing what customers download, the country's top two pornography providers, Hokuto and Soft on Demand, say sales to cellphone users are driving revenue growth.
"Pornography will eventually open a debate about how carriers should modify their business model as data traffic swells," says Yusuke Tsunoda, a telecoms analyst at Tokai Tokyo Securities.
"It may prompt even tighter access restrictions."
Japan rolled out so-called third-generation, high-speed cellphone services in 2001, two years before the US.
Now, more than 91 million Japanese surf the internet by cellphone, downloading games, movies and music, according to the Tokyo-based Telecommunications Carriers Association.
Juniper estimates internet usage over phones in Japan is three times the level of the US.
Juniper says the problems Japanese carriers face may spread as consumers demand more movies, music and other data-intensive downloads, including growing access to sites with adult content.
Mobile porn boom
Global revenue from pornography on cellphones will more than double to $4.9bn in the five years to 2013, while music sales will grow by about a third, according to Juniper.
"We can't see customers' data, but can surmise the biggest portion of it is probably movies," says KDDI spokesman Keiichi Sakurai. "We can't deny the possibility those movies include adult content."
He says customers have complained about stoppages or slow web access, mainly around midnight when traffic from "heavy users" spikes.
Japanese carriers have spent $74bn building their networks since 2000, according researcher Wireless Intelligence.
Japan has more than 1 000 firms producing adult content movies, generating about 17 000 titles last year, according to Tim Smith, who has worked in Japan's telecoms industry since 1999 and is chief executive of 3G service company Sairis Group.
Smith says the top Japanese adult content internet sites have as many as 1 000 new customers a day, each paying as much as ¥10 000 as a sign-up fee.
While music downloads are the "official big earner" in Japan's mobile commerce, more money is made through porn, dating sites and even fortune-telling services, says Smith, whose firm has helped run promotions in Japan for Viacom's Paramount Studios, Toshiba and MasterCard.
Revenue at Soft On Demand's cellphone site, which offers free movie samples and DVD sales, surged 40 percent in the year to March and now totals about ¥15 million a month, says Hirotaka Ishimori, the head of its online division.
Huge market
"We see the cellphone as potentially a huge market," Ishimori says. "Fixed-rate data plans, faster internet access and sophisticated handsets are contributing to that growth."
Ishimori estimates total annual sales in Japan's pornography market are ¥100bn.
The unlisted Tokyo-based porn producer had ¥14.7bn in sales for the year to March last year, according to company researcher Teikoku Data Bank.
Revenue at market leader Hokuto is more than twice as much, Teikoku Data estimates.
Hiroshi Tojo, the head of mobile sales at Digital Media Mart, which operates Hokuto's online outlet, says the mobile porn market is "still relatively untouched".
Hokuto's website offers two-minute video clips for phone users for as little as ¥100.
"Whenever there is a new distribution method for adult content, adult content will go that medium," says Holden.
"It's gone that way since cavemen drew adult pictures in the cave." - Bloomberg
