I couldn't find any badging. From the design of the dash and a few other minor details, I got the impression it was Japanese. Nothing definite though.I would still be willing to bet that one pictured above (carcass) was an American built Willys. You never said if it had any badging to determine if it was truly a Mistu.
So, I did some digging and found this.........look mid page
Jeep CJ - Wikipedia
en.wikipedia.org
I did not seeing anything about if they were exported from Japan or not?
Interesting history though