I’d find it interesting if Nagant was thrown into Tartarus because she disagreed with the HPSC. The HPSC has definitely done dirty things and my theory is, Nagant opposed whatever the HPSC was going to do which would then lead to her arrest and her betrayal to the HPSC.
This would be really...
I agree that he’s beyond saving and he went too far and he’s %100 responsible for his actions but it did surprise me how Natsuo, Fuyumi, and Rei aren't even going to even attempt to help him.
..especially since they’ve never seen him doing anything terrible in person.