In Kakifly's tradition of naming characters based off bands(the main 5 girls from P-Model, the side characters from The Pillows), it seems the new college girls' surname(and if you're Kanji savvy, part of their given-name) are from these guys.
http://en.wikipedia.org/wiki/Triceratops_(band)
With this, we can make an estimate of what instrument the girls play as well.
Akira plays guitar.
Sachi plays bass.
Ayame plays drums.