According to government data, 80 percent of e-commerce by teen-agers aged 15-19 was done on cellphones in 2005.

[...] "One of the changes that came with the 3G services is an increase in flat-fee users," said Jun Hasebe, an analyst at Daiwa Institute of Research. "Impulse shopping accounts for most of the purchases done on mobile phones, and that would not usually happen unless users are on flat fee-based services."

[...] One of the issues that may hold back those could-be shoppers from using mobile phones is safety. Many Japanese consumers still fear punching in their credit card numbers online or on cell phones.

More than half of e-commerce sales in Japan were paid with cash rather than electronically in 2005, while 13 percent were settled with credit cards, government data shows.