Grandpa Coin Collection - Part 1 of 4

My wife's grandpa was in World War II (Okinawa) and part of occupation force in Japan and China.  He died a few years ago and never talked about the war.  We found the following collection in his items from the war.  I believe some are from Japan and some are from China.  There are 17 different types of coins.  I have four scans.  If anyone can help identify them, I would be greatly appreciative.

Thanks.

1. https://en.numista.com/catalogue/pieces14005.html
2. https://en.numista.com/catalogue/pieces5435.html
3. https://en.numista.com/catalogue/pieces13956.html
4. https://en.numista.com/catalogue/pieces9581.html

The third one is pretty rare, your grandfather was lucky to get ahold of it. Even I don't have it, even though I'm Japanese myself.

Thank you very much SmartOneKg.  This is great stuff.  I will mark these down. This was extremely helpful.