In theory, you should carry your passport or ID at all times and the police have the right to arrest anyone who fails to do so. In practice, however, they rarely stop foreigners, though car drivers are more likely to be checked. If you're found without your ID, the usual procedure is to escort you back to your hotel or apartment to collect it. Anyone found taking drugs will be treated less leniently; if you're lucky, you'll simply be fined and deported, rather than sent to prison.

The presence of police boxes ( koban ) in every neighbourhood helps discourage petty crime, and the local police seem to spend the majority of their time dealing with stolen bikes, and helping bemused visitors - Japanese and foreigners - to find addresses. This benevolent image is misleading, however, as the Japanese police are notorious for forcing confessions and holding suspects for weeks without access to a lawyer, and recent Amnesty International reports have criticized Japan for its brutal treatment of illegal immigrants and other foreigners held in jail.

Racial discrimination can be a problem in Japan, especially for non-whites, though it is mainly directed at immigrant workers rather than tourists. Sexual discrimination is widespread, and foreign women working in Japan can find the predominantly male business culture hard-going. The generally low status of women is reflected in the amount of groping that goes on in crowded commuter trains - there are even pornographic films and comics aimed at gropers. If you do have the misfortune to be groped, the best solution is to grab the offending hand, yank it high in the air and embarrass the guy as much as possible. Fortunately, more violent sexual abuse is rare, though rape is seriously under-reported and may be up to ten times higher than the current statistics suggest (under 2000 cases per year). Women working in hostess clubs are particularly at risk, as the murder of Lucie Blackman in 2001 sadly goes to prove. In the wake of the publicity, several other women came forward to make accusations of sexual abuse, that often occurred after they were drugged.

If you need emergency help, phone 10 for the police, and tel 119 for an ambulance or fire engine. You can call free from any public phone by pressing the red button before dialling, though with the old-style pink or red phones you need to put a coin in first to get the dialling tone. Better still, ask someone to call for you, since few police speak English. If you get really stuck, Tokyo Metropolitan Police operates an English-language hotline on tel 03/3501-0110 (Mon-Fri 8.30am-5.15pm), while the 24-hour Jhelp.com (tel 0120-461997, www.jhelp.com ) handles emergencies as well general enquiries. Each prefecture also has a Foreign Advisory Service, with a variety of foreign-language speakers on call who can be contacted as a last resort .