No prizes, though, for guessing what is the top trouble-maker: the mobile phone.
In Japan, there are more "keitai denwa" in circulation than there are regular land lines - 74.8 million mobiles to 50.7 million fixed lines - and the cut-throat nature of the business means that makers are obliged to put out new cellphone models within months of their last one hitting the streets.
It's partly fashion - six months is an eternity to the average teenager or twentysomething with cash to burn. But it is also technology driven.
Spoilt for choice
Go into a mobile phone store in Japan, and the only choice you don't have is whether to have an integral camera. It is now standard. Everyone from pre-teens to pensioners can be seen thumbing out text messages to go with a photo that they're e-mailing to a friend.
People of all age groups can be
seen typing out text messages
But even that is passe now; the new in thing is video mobile phones, while others are equipped with GPS mapping systems.
Some cellphone models under development are able to stream television programmes. They're not expensive - around Y10769 ($100) a time - and they're small, sleek and fashionable.
And they're causing no end of trouble. Once an important business tool, the mobile phone has been hijacked by conmen and perverts.
In late April, a Japanese housewife was fooled into parting with millions of yen in cash by two confidence tricksters with the tried-and-trusted Ore! Ore! scam.
The trick involves a phone call out of the blue, usually to an elderly person, and a quick-fire burst of "Ore! Ore!", which can be roughly translated to "Hey! It's me!" - that the victim assumes is a relative.
The target was a 54-year-old woman from Wakayama Prefecture, in central Japan, who apparently missed the police warnings to beware of suspicious phone calls and the extensive media coverage the con had generated.
The woman, who has not been named, reportedly received a slightly muffled call on a mobile phone from a man who she thought was her son begging for some cash to be transferred to a bank account because he had fallen foul of a money-lender.
"As a telecom carrier,
we cannot check or stop e-mails that individuals send to each other. Malicious e-mails are
a question of users'
Statement issued by NTT DoCoMo, Japan's largest
mobile phone company
The unsuspecting mother promptly deposited Y1.4 million ($13,000) into the account. Shortly afterwards, she got another phone call saying it was not enough and demanding another Y1.5 million. Dutifully, she complied.
After hearing nothing more from her "son", who lives in Osaka, she became suspicious and contacted the police. A couple of phone calls quickly confirmed that her real son was not in financial difficulties and that the account she had sent the money to had been cleaned out.
In the first 10 months of last year, the National Police Agency said it investigated nearly 4,000 "Ore! Ore!" calls, with 2,768 succesful calls earning the con men some Y2.26 billion ($22 million). Just 39 people were arrested in the same period in connection with the scam.
Police have urged people who get frantic phone calls asking for money to at least call the person who is claiming to be in trouble back again to confirm the story before parting with any cash.
Con men are not the authorities' only headache, however.
Last year, Japan's Justice Ministry desperately tried to block the circulation of mobile phone e-mails containing the name and photo of a 12-year-old boy who admitted throwing a boy aged four from the top of a multi-storey car park in the southern city of Nagasaki in July.
Under the Juvenile Crime Law, the boy could not be identified as he was under the age of criminal responsibility, which is 14 in Japan. But that did not stop the photo and his identity being displayed on internet bulletin boards and passed on among mobile phone users.
Mobile phones in circulation far
outstrip the number of land lines
On 1 July, the boy abducted Shun Tanemoto from an electronics shop and later killed him in a case that deeply shocked a country famous for being law-abiding. The boy was also questioned in connection with a number of assaults and for sexually molesting three other young boys.
On the grounds that identifying him was a breach of his human rights, the ministry and the Nagasaki City Government asked the operators of the sites to delete the messages as soon as they appeared, but they were unable to break the chain because the data was being forwarded via e-mail to thousands of other addresses.
"As a telecommunications carrier, we cannot check or stop e-mails that individuals send to each other," an official of NTT DoCoMo, Japan's largest mobile phone company, said in a statement at the time. "Malicious e-mails are a question of users' poor manners."
Photograph-capable mobile phones also have a large following among the innumerable "chikan", which is best translated as molesters or perverts, who find plenty of opportuntites to indulge their hobby on Japan's famously crowded trains.
Late last year, a man who set up a support group for men who complain they have been falsely accused of molesting a woman on a train, was arrested for allegedly using a mobile phone to take a photograph up a woman's skirt.
Mitsuru Nagasaki, 47, was grabbed by passengers after they noticed him aiming his mobile phone up the skirt of a woman sitting opposite him on the Oedo subway line in Tokyo. He was handed over to the police and arrested on suspicion of being a public nuisance.
Some phone users have been
tricked into parting with cash
Nagasaki has been a voiciferous campaigner for those branded perverts, claiming that The Group to Support Men Falsely Accused of Being Chikan wants to support other men trying to clear their names and their families, demand fairer investigations by police, and lobby rail companies to introduce more measures to combat molesters on trains.
The 13 founder members of the group are awaiting trial or have been cleared of charges of molesting women.
The chikan problem has become so bad that two private rail companies in Tokyo have introduced women-only carriages late in the evenings, when trains are full of tipsy office workers and when 70 per cent of groping complaints are made.
West Japan Railways has had to introduce a morning women-only service to protect female commuters from early-bird gropers. The service runs between 5am and 7am in and around Osaka.
Female commuters have grown
wary of cellphones with camera
Nagasaki claimed he was returning home after distributing the group's leaflets when he was arrested and initially denied any wrongdoing. But later he said he was too drunk to remember what he had done, according to police.
With evidence ironically including his mobile phone and the images stored in its memory, Nagasaki was convicted in February and handed a six-month suspended prison sentence.
The conviction was Nagasaki's second on similar charges; it remains to be seen whether he has been cured of his predilection for phone sex.