I might be wrong, but I think the black haired girl choose to commit suicide instead of an arranged marriage. (kind of retarded, lazy writing, whatever)
The ending is after a timeskip of at least 10 years (crt TV -> LCD TV), seems like the blonde girl couldn't bear it, and broke down mentally.
edit:
I shouldn't scroll that fast next time. After taking a second look, its kind of confusing. There is the old tv, and the rotary phone. So decades passed, yet the girl looks younger than before. And she don't know Mihoko, and since a name change is very unlikely, its not amnesia.
Might be missing a supernatural tag, I am not sure.
I am probably overthinking things. It could be just a "normal" nightmare.
To be honest, I really liked this one. Most of the Galette oneshots kind of empty, with an "open ending" (means unfinished
), but this one made me think. It doesn't makes sense, but at least it made me think.