As much as I would love Aika to join, I don't know if they would put her in if they're trying to audition for a singer/guitarist. Unless she plays something. Tamborine? I don't know.
They can't have a band without a bass player, that would just be a travesty. So for now, since they didn't audition a bass player, I'm just going to assume Aika is being put on bass/Backing vocals
(P.S UFA this probably needs to happen so Aika can be doing something and not be H!P in name only)
^ Tendinitis is more of a concern for bass players than fractured wrists. I don't think that instrument would present any special problems for Aika.
Also, I have a theory about bass players. There are two types of bass players who actually add value to a rock band. The first is a bass player who isn't very good and knows this and knows to stay out of the way of guitar player and singer and stay in the pocket. The second is a virtuoso bass player who knows enough to know that he's not the main attraction and tastefully adds some pizazz here and there and basically only does about 10% more than the first type. Aika could probably achieve the first type. She could also wear some rock&roll clothes, sing back up and add value to the group.