By Edward Shawn Edward Shaw is an I-OnAsia consultant and Japan country expert. He is a retired FBI Agent and former Tokyo Legal Attaché. I-OnAsia regularly provides support to Olympic visitors.

How can an American avoid arrest while in Japan?
First and foremost, behave as a lawful citizen in the U.S. and you will be fine 99.99999999% of the time.
However, some activity that is not a crime in the U.S. is a crime in Japan or could be perceived as a crime.
Below are some of the most common situations that might lead a law abiding American to be arrested in Japan.
1. FIREARMS: Possession of just one round of ammunition in Japan is a criminal violation equivalent to a felony.
• An American once travelled to Japan and used luggage which he had previously used during a hunting trip in America. Japanese customs officials found the one round of ammunition in his luggage and he was arrested.
• In addition to ammunition, possession of any part of a firearm (e.g., an ammunition magazine, custom hand grips, etc.) is also a serious crime.
• Possession of a fake but authentic looking firearm is also a crime.
2. KNIVES: Japanese law forbids possession of a pocket knife with a blade longer than 6 centimeters. Lots of Americans always carry a multipurpose pocket knife or a pocket sized multipurpose tool that includes a knife. Don’t take those to Japan.
3. TATTOOS: Men, if you have tattoos, dress in a manner that covers the tattoos.
• In Japan usually only Japanese mobsters (Yakuza) have tattoos.
• If you have visible tattoos (especially if you are an ethnic Asian male) you do face the risk that the Japanese police will mistake you for a Yakuza criminal suspect.
• Japanese law allows any business (restaurants, pubs, etc.) to ban any guest, man or woman, with a visible tattoo. This is how these businesses avoid gangster customers. If you have a visible tattoo you can be lawfully ejected from a business.
• If you don’t follow the employee instructions to leave, you could be arrested.
4. HERO: The writer knows from personal experience of two incidents when other foreign national men in Japan came to the assistance of a “damsel in distress”.
• In one instance an American man saw a thief snatch a purse from a woman and the American chased the thief. Simultaneously, the victim was able to tell a nearby policeman of the crime.
• The policeman saw the American running from the scene of the crime, assumed he had snatched the purse, and arrested the American while the actual thief escaped.
• If you see a crime while in Japan, report it but do not intervene.
5. MEDICINES: Be careful with your prescription medications. Especially if you plan to travel to Japan with a supply of a medication that is heavily regulated in the U.S.
• In 2015 Julie Hamp, then a Toyota executive, secretly shipped oxycodone to Japan. The shipment was discovered and Hamp was arrested. More information about her arrest can be found here. Japan Arrests American for Drug Violation