I have a feeling that before the author came up with the story for this, he/she challenged him/herself out of laziness to make a story where he/she wouldn't have to think of any names for the characters.
I kept expecting the blonde girl to jump the JK like some male rapist after wich I expected the dark-haired JK to cry and tell the older girl that she pretends to be her own shadow because she's afraid to talk to people. Reading too many cheap yuri manga written by nutcases will do that to your expectations.
Finally some good yuri with realistic and interesting characterizations for a change. This was a great story.
Well, for a whirlwind romance of a sort, I guess it works. One really is left with no idea if they'll actually get along thereafter, though, with so little interaction.