1. Don’t tip anyone.
2. Don’t go into people’s homes with your shoes on.
3. Don’t forget to take off the special toilet slippers once you leave the toilet room.
4. Do not enter a bathtub without washing yourself outside the tub first, especially at onsen springs, or at public baths (sento).
5. Don’t try to hug people you just met.
6. Don’t talk on your cellphone in trains.
7. If someone invites you to dinner or drinks or something (e.g. after a business meeting) they will be doing the paying,
8. Stay on the correct side on escalators.
9. Don’t drink or eat while walking around
10. Don’t eat on commuter trains.
11. Even though you will notice that trash cans are quite scarce on the streets of Tokyo, do not litter.
12. There are lots of much less critical cultural faux pas I could mention, regarding chopsticks and all that.
13. Do not bring in any illegal recreational drugs with you.
14. Likewise, don’t try to bring in firearms or other weapons like swords
15.Don’t get arrested and convicted in Japan and sent to jail