Under the scheme, perpetrators emailed bogus bills for online adult use using the prepaid mobile phones, which allow for anonymity.
Kyodo News reported that Tokyo has tracked down 291 mobile phone numbers used in fictitious billing schemes and has requested that their service providers cancel the phone numbers.
Vodafone K.K., the largest prepaid mobile phone service operator in Japan, has received information about 200 such phone numbers and has already canceled several of them earlier this month.
As a result of the schemes, government leaders plan to craft a bill requiring users of prepaid mobile phones to provide personal identification documents at the time of subscription.
Vodafone officials said most users of prepaid mobile phones in fraudulent cases are unidentifiable. It sent email messages to those mobile phones warning that the phone service will be shut down unless the users provide personal identification documents.
Vodafone shut down services for some of those numbers after their users failed to submit personal identification documents after a few weeks, company officials said.
There are an estimated 2.7 million users of prepaid mobile phone services in Japan.
NTT DoCoMo Inc. of Tokyo has already decided to end the service.
