I know next to nothing about error coins, but lately have found a few interesting Japanese ones. I'm not sure about this one, but got it fairly inexpensively in an auction mixed in with other coins. I'm hoping to add it to the Japanese error thread on the world coin forum, but not sure. Opinions?
That is definitely a clipped planchet mint error! You can see the Blakesley Effect across from the clip. Weakness on the rim.
What's the Blakesley Effect? Perhaps I need to break out the google-fu . edited to add: Interesting reading, and now I am even more happy with this one (heads off to post on other thread). https://www.australian-coins.com/error-coins/how-to-determine-if-a-clipped-planchet-error-is-real/
The Blakesley effect is the Weak Rim completely opposite of your curved clip. It isn't always there depending on the type of clip and position in the chamber.
