^ I thought Chisato's outfit looked familiar too, but only because the style in general is so similar to looks we've seen before.
- The sweater looks really similar to the one she wore in the story parts of the "Campus Life" PV.
- The style is similar to one of the outfits S/mileage used during "Shortcut" and (like you said) one of Erina's "Ai BELIEVE" outfits.
I think my favorites are Maimi and Mai, which.. I don't think has happened before. I really love Maimi's though.