I doubt she truely wants to leave and that sucks. The people that are complaining that she's tacked on to Gaki's grad are also being insensitive. Unless you yourself have ever been told you need to stop doing something you love because of injury and disability stemming from that you can't understand how that feels and how hearing people complain and be dickish is just kicking the dog when it's down so to speak.
Maybe if they had stuck with the original plan of a 5th gen joint grad then Aika would have got her own grad in spring it seems like them keeping Gaki on to train the kids threw a spanner in the works and they have decided in the end to graduate her in spring anyway. I would hope that she gets proper treatment and not just a quick footnote where she gets some flowers and them they usher her away so Risa can have her big moment.
At least she could have goods and a graduation DVD. And even if she had to sit down for it let her sing and have a moment in the spotlight. It'd feel kind of crap if it's like "Okay yeah you're like disabled now so you can't work, Have some flowers okay bye"