And I believe the mangaka wrote this for a Japanese audience.
Right--the theme of the generational difference between attitudes toward lesbianism is very convincing, as I said. The issue for me is that the story mechanism of how this experience of the past got into the dreams of the present-day character, and why this specific character is having those dreams, is not particularly clear.
I expect most people have had recurring dreams to some extent (I certainly have at times), and that strange sense of being familiar in a dream with someone or someplace you've never actually seen in real life is, according to reports and my own dreams, incredibly common.
If a Japanese audience would see such elements in this story and automatically assume, "Oh, those are past-life memories from her previous incarnation a generation ago," that's a very interesting thing to find out about such cultural differences.