I really feel like you guys in the comments here are being unfair and harsh to these girls by excessively vilifying them for things mostly out of their control.
First of all, Fana has exactly zero blame here. She wasn't involved in the banishment at all, and she has no attachment to Shin initially to try and defend him or keep him around. She's as much of a victim of Raid as he is. And of course she wants to bring him back mainly for his skills, what with her goal of being S rank. Adventuring is a dangerous profession where one's skills, strength and ability are literally a matter of life and death. Pragmatism trumps blind loyalty if you want to stay alive.
Secondly, Nina and Lena are only worried about keeping Shin safe. Nina because Shin at least APPEARED to be weaker than them, and Lena because she knew that Raid was intentionally putting Shin in harm's way (and because Shin appeared to be weaker). They were only looking out for his health and life. It's not like they were abusive and mean to him.
Sure, they all could have talked to Shin more, but this entire situation was always and ever Raid's fault. He was the weakest link in the party and the catalyst for everything bad that happened to Shin. He deserves 99.9% of the blame for everything.
I'm sure these girls will do what they can to atone for being party to kicking Shin out of the group.
Sexually, that is.
Tbf, it's not that he appeared weaker, he was. Because he was buffing the other 3 instead of himself.
Now, about Nina and Lena...that's just the usual "for the sake of plot" imo: you're worried for his well-being, so you send him to the unknonw on his own because your party leader said so? What if he joins a random party and dies during a quest? Did leaving him on his own save him?
Those 2 choose fame over him saying it was for his best, when if they really cared for him, they would have stayed with him, either banishing raid or leaving the party. More so when, iirc, Raid was the last member to join.
About Fana....well, she got scammed. That's crystal clear. She was presented a rank A going for S party, but found a rank C party.
But the moment she realizes Shin is actually the strongest, she starts plotting to legit use him.
Sure, adventuring is a risky job, but a trusty teammate goes longer than riding tailcoats. Even more when she (as of now) didn't bring anything to the party (as for Raid words).
And from chapter 1, we already know what her plan is
So, even if that's what the story is about and adding that Raid is scum with most of the faults, these 3 girls aren't just victims.