I don't see any problem with the frog. Showa 16 (1941) and the encircled "Dai" mark is a mark I've seen on T-14 holsters. I don't think it has anything to do with Osaka. Osaka stuff is either marked with the crossed cannons or the "saka" marking. I don't see a Nagoya mark, just a circle. The lowest mark looks like the "Kyo" mark to me (for To-kyo).
Until Okiedokie shows up I'd say it's most likely a contract production item inspected by Tokyo Arsenal.
Until Okiedokie shows up I'd say it's most likely a contract production item inspected by Tokyo Arsenal.
