These stories occasionally make national news, I've probably read two
in the past month: even tens of millions of yen may be reported placed
in people's mailboxes or on their doorsteps in envelopes or by the
shopping bags-ful. Alternatively, people find large amounts of cash,
once even hundreds of millions of yen in solid gold bullion plus cash,
are reported simply lying on the street, miraculously not spirited off
by other or previous passersby.

Are people this damned careless or forgetful in Japan? Or is there some
ulterior motive behind it? For example, someone is trying to bribe the
occupant or give them a subtle hint about some business deal or
upcoming election, and the occupant cluelessly turns the money over to
police. Or alternatively, the bribe is deliberately made in the form of
an "unexplained find", and the occupant is free to receive the
"unclaimed" money later. If anyone I ever met actually misplaced such a
large amount of money, you can be damned sure it wouldn't go unnoticed,
and they wouldn't let it go unreported, the way that one guy was able
to claim the 300 million in gold plus cash he said he found on the
street, as I assume gold bullion is serial numbered.

Any clues?