I dont think golden axe is japanese.. japanese system 16 versions dont have mask roms.
And he is one of the coolest ninja ive know !you have an amazing collection of cabs.
Every day is a school day I guess. Generally most of the system 16 Japan games ive seen were eproms a bit like the cps1. I just assumed that they were all like that. Perhaps a later re run or something as Golden axe was a poplular game. Im not sure which Eproms contained the region code but if those are eproms then it would support my theory that it was a rerelease using world mask and JP region code.