Hi Gavin, thanks for taking the time to re-live the experience, I can only hope it will be something you laugh about in the future when you look back and think you went half way around the world and back in such a short time, an epic experience.
Sorry how its panned out, sounded so promising when I started reading, I can imagine having the same reaction as you did when you received her call, numbing for sure, we would all feel the same. I wouldn't begin to guess at her reasons as like you and everyone else have said it just doesn't make sense, aunt from Chicago just doesn't ring true to me.
I wish you had said you would go with her to collect her belongings, wonder what her reaction would have been. Maybe like its been suggested she just doesn't know her own mind and is immature and unable to cope with the situation. Only she knows.

You didn't say if the guy waiving at the airport was a friend that had accompanied her?

Not much else I can say really thats not been said already, seems you have coped rather well considering.
To travel the distance you did for a lady is a big deal (as I often remind my wife :-) the way that girl treated you is beyond words, i hope you can start planning your Japan trip and just forget about this saga.