You've got to be a special kind of idiot to try to molest teenagers on a crowded train, relying on them staying quiet out of embarrassment, in a world where tiny people can pop up who yell out what everyone knows is the true feelings of the person in question. I'm not sure the author thought that premise all the way through to the end.
If it has been advertised as yuri, maybe one sister ends up with the boy but the other ends up with another girl? The new girl with the glasses asking if they are familiar with him initially comes off as her potentially liking the boy, but it could be to make sure they aren't interested in him? Just spitballing.
Cupcakes!
Random Dog!
Nicknames! ROFL
I still need to get used to the clone BS. It's gonna be hard getting over it that this plot device exists.
But I shall prevail! For my incest yuri!