In typical Japan style, the airline staff were lovely and went out of their way to try and fix this issue.
But over their dead bodies would a model take a seat reserved for a human.
The original ticket (not purchased by me) had to be refunded. An ENTIRELY new baggage ticket must then be bought (by me).
Concern 1: what if the new ticket --due to its last minute nature--was more expensive than the original? This should really be discussed but the clock was ticking ⏰