Wow, I did not notice that little mark! Thank you!
I'd known since I was a kid that my Dad had this sword, but never gave it a thought. Only after my Dad passed away, and then my Mom gave me the sword before she passed away, did I take a closer look at it. This has been quite a learning experience!
Thank you all for your feedback. I'll take additional photos next weekend. I can't do it now because I've suddenly been drafted to lead a 4WD camping trip starting Tuesday, so I need to formulate a route and map some coordinates.
My late father acquired this gunto while serving in the U.S. Army during the Korean War. He was stationed in both Korea and Japan. He went to the PX for cigarettes, saw a pile of these in the back, and asked the guy if he could have one. I removed the handle and found these characters and numbers. Can the year and maker be identified from these?