I live in Japan so even if i lose something the chances of me getting it back is probably higher than most other countries. I lost my bus pass on the bus a few months ago and I actually got it back within 2 weeks which was impressive and i was very grateful. Ive forgotten things on airplanes and within a month it had been shipped back to my house. I have lost things and they did not make it back but that was once out of losing things many many times. If you ever travel to Japan, if you call the correct authorities and ask politely, you will (most likely) get your things back.
Ive helped friends get things back after losing various items on public transport and because Japan is relatively safe, its pretty unlikely your things will get stolen before it will get collected by the correct authorities. If you lose it on the bus, depending on the bus company, there will be a number on their website you can call to ask for the lost property department. If you cant speak Japanese it may be best to ask someone who can because the people on the other end of the number, I doubt they will be able to help as much if theres a language barrier. If you lose it on the train (not a Shinkansen), it is best to go to either end of the line or go to the stop you got off of and ask the station staff. Train staff, at least in Tokyo, are better suited with foreign languages because they do get asked for directions in other languages often.
Look out for this “落し物” it literally means dropped things. If there is a sign in a station somewhere that says that, its best if you go to that sign and ask anyone nearby and try to tell them you have lost something.
SO, if you do lose something in Japan, don’t worry. Its scary to lose something in a different country but Japan is super safe and careful when it comes to lost properties.
This was a short post inspired by the countless number of times I’ve had to call in for lost items, mine and for others.