Producer’s note: Someone on Quora asked: What should I absolutely not do when visiting your country? Here is one of the best answers that’s been pulled from the thread. Thank you to the team at Quora for making this happen!
1. Don’t tip anyone. No one. NO ONE.Tipping is just not part of the culture. Don’t even leave the small change. People will come running after you with it. Seriously. (See: How does tipping work in Japan?, also No Tipping: Japan vs. Europe.)
2. Don’t go into people’s homes with your shoes on. You may run into this at certain temples and shrines, restaurants or traditional inns too. If you see other people taking their shoes off, do the same. (Note: there’s a small area right inside the entrance called a genkan which is usually one level below the rest of the house, where you take off your shoes. You don’t take them off outside the house!)
3. Don’t forget to take off the special toilet slippers once you leave the toilet room. You will encounter washlets or toilets with attachments for washing and drying your private parts everywhere. Don’t get too freaked out by them…and if you can’t figure them out, you can always use toilet paper. (See: Am I the only one who was taken aback at first when viewing the toilet choices in rural Japan?)
4. Do not enter a bathtub without washing yourself outside the tub first, especially at onsen springs, or at public baths (sento). (A lot about various hygiene related things here: Japanese Culture: What are some of the Japanese hygiene habits which the rest of the world should know?)
5. Don’t try to hug people you just met. Most people don’t like it, especially older folk. (See: Cultural Faux Pas: What ethnic groups/cultures are (generally) uncomfortable with hugging?)
6. Don’t talk on your cellphone in trains. While it’s not against the law, it’s considered to be rude since it disturbs people around you. Likewise, don’t talk in loud voices in the train either. Talk in a low discreet voice (or a regular conversational tone – don’t shout at at each other).
7. If someone invites you to dinner or drinks or something (e.g. after a business meeting) they will be doing the paying, so don’t keep insisting that you’ll pay.
8. Stay on the correct side on escalators. In Tokyo, you stand on the left. In Osaka, you stand on the right. Follow what other people are doing.
9. Don’t drink or eat while walking around unless it’s at a venue where that’s expected, like a festival with food stalls (although even there people usually eat sitting down).
10. Don’t eat on commuter trains. Drinking discreetly from a PET bottle is okay unless it’s too crowded. (Eating and drinking on long distance trains is fine though, since you have pull-out trays and such. They’ll even come to your seat to sell you food and beverages.)
11. Even though you will notice that trash cans are quite scarce on the streets of Tokyo, do not litter. Carry your trash with you until you find a place to throw it out. (See: Tokyo: Why are there no trash cans on the streets in Tokyo?)
12. There are lots of much less critical cultural faux pas I could mention, regarding chopsticks and all that. But most behavior is forgiven (or rather, tolerated…) if you are a foreign visitor. For instance there’s not a whole lot of PDA (public displays of affection) in Japan, but if two non-Japanese people are kissing, most people just think it’s cute.
You should not break the law in Japan.
1. Do not bring in any illegal recreational drugs with you. This includes marijuana. Japan has very strict anti-drug laws…you’ll most likely get deported, although you may be ‘detained’ for a long time, or put in jail.
(Prescription drugs are generally OK, but if you are not sure, ask the Japanese consulate in your country beforehand. Bring your prescription with you just in case and leave your medicine in the original bottles or packages. There are restrictions on alcoholic beverages and tobacco amounts you can bring in as a tourist, as there are in most countries.)
2. Likewise, don’t try to bring in firearms or other weapons like swords or something unless you have a special permit to bring in an antique or something like that. (This should be common sense, but…)
3. Don’t get arrested and convicted in Japan and sent to jail (and you won’t always get rescued by your country’s consulate either). Japanese prisons are not brutal, violent places, but they are very Spartan, and there’s no parole for good behavior. 
