Is it me or the main character seems already aware of her own orientation?
Like, she gushed over how pretty the girl she bumped into was and the mom didn't seem that surprised, as if that was a common occurrence.
Yes, I know this should be seen as normal, I am pointing that out from a narrative perspective, because to make the MC first notice she has feelings for another girl, especially in Japanese media. It would be an interesting change of pace to make her already aware of her preferences.
As for the second MC, at first, it seems her detachment is a bit excessive, but again we have to remember the place this story comes from, in japan, being different from is not a good thing. To the point segregation is a regular response from society (Just watch "The sound of her voice" for an example) thus her being a bit cynical about MC trying to befriend her is not that much of a stretch, plus whatever other baggage she may have.
For now, I think this has the potential for a good story and look forward to what will happen.
Also: I never heard that saying before, to see the moon in the rain.
I will remember it.