While doing a transfer on the Shinkansen in Hiroshima, I left my camera bag at a noodle kiosk on the platform (around $3k worth of equipment). Didn't realize it until 2 hours after getting on the next train.
When we arrived at our destination, I told my friend we were meeting (a Japanese native) what happened, and she reassured me that it would be right where I left it (said something about there being a "taboo" with the Japanese and touching other people's private property).
So we walked over to the JR attendant and explained what happened, and in no time at all she had the other station attendant on the line who confirmed they found my bag. Just as easy as that.
Then I proceeded to lose my wallet and passport in a taxi, which we recovered just as easily!
Japan is a great country to visit, if while abroad you displace the part of your brain that keeps track of things...