I’ve watched this video of a guy who conducted a social experiment in Japan to test people’s honesty whether they’ll either point out he dropped his wallet or ignore which makes it prone to theft. For the most part, people just returned it back to him.
You can’t really generalise an entire nation like that. It is 100% up to the person.
I have seen both sides wallets returned and not returned. Before Facebook they generally ended up at a police station but since then it usually ends up being a message or call on Facebook Messenger.