Okay, the PCs will be Yuki, Noriko, Minato, Shef, Yoake, and Faith.
Faith fits into the party very well. She has powerful ranged attacks (while her Ranged stat isn't too high, it's focused on blasts and her Hypers making it more powerful than you'd expect from a 4 in a stat normally, plus her Requiem empowers it further) which helps fill a gap in the party, especially with that area of effect skill. Plus she has a connection to Yuki which can lead to quite interesting roleplay, and is also the same age as Fuuri so she can keep her company during class and whatnot.
Shef doesn't fit as well into the party being a 28 year old jaded weapons distributor, but... he has decent ranged options, useful contacts, has skills and age that make him good at acting as a "face" for the party when dealing with civilians, especially since his Requiem can help force civilians to get out of danger they may not even notice. Also, he contrasts very nicely with Minato.
Yoake has a pretty damn versatile and interesting Requiem, seeing as it can be used for combat, mobility, or just limiting collateral damage, so she works well with Faith, Shef, and to a lesser extent, Noriko. She has interesting interactions thanks to her returning from that island to show the world Keijo, which also likely makes her work well with Minato whose activities have generated gossip, and Yuki who can be pretty bombastic.