OK, here's one for you - checked my "recent qsls" today and
surprised to see a confirmation for a JA3 on 6m FT-8.... nice,
except I never worked him. Have one JA on 6m and that was a
JA0 earlier this year.... rechecked my log and - nope, only 2 
contacts that day - both stateside.
So.... mystery!  Any ideas?  Rick AI5P