I found this old coin in my wallet last week. It is a 5 yen coin from 1949. Way back then, the 5 yen coin didn't have a hole in it. I don't remember where I got it from, probably as change from a store or a convenience store.
I thought that it might be valuable, so I looked it up on the internet. It is worth about 100 yen, according to one website I looked at.