In most parts of Tokyo if you drop your wallet on the street somebody will chase you down to return it.
Umbrellas? Not so much. Stealing umbrellas is the official city pastime in Tokyo. Turn your back for one second and that thing will be gone. Report it to the cops and they'll just tell you to steal somebody else's.
This is actually a good thing from an environmental perspective. Japan has the type of downpour which can thoroughly drench you (in July for instance), but most of the time you don't need an umbrella. Obviously this means that umbrellas get lost, misplaced, or forgotten. If no one just took any seemingly lost umbrella out of politeness, you would end up with thousands of them going to a landfill.
I had the same thing with my umbrella when I left Japan after a year of studying there. “What should I do with this? It's still a good umbrella.”, “Oh, just leave it at the station, someone will take it.”
In 2024 I have visited Japan. It happened that when we changed quickly the subway train in some station, one of us has forgotten his expensive smartphone in the other train.
Someone from the old train has noticed this and she ran very quickly to our new train, returning the smartphone to the owner. She had to run very quickly between the 2 trains, otherwise her train could have departed, but she succeeded to go back.
The weird thing with the subways is you can ride around on them all day as long as you have a ticket that covers the fare from where you entered to where you leave.
A lot of the stations didn’t have shops, and a lot of those were outside the “turnstiles”, but there are some places where for lulls you could change trains to get a drink or a snack then backtrack to where you were “supposed” to get out.
So someone chasing you down is just lost time, not lost money.
Umbrellas? Not so much. Stealing umbrellas is the official city pastime in Tokyo. Turn your back for one second and that thing will be gone. Report it to the cops and they'll just tell you to steal somebody else's.