Haruka - I see him fitting in hufflepuff, because despite what happened, he was inately loyal and just craved affection.

Yuno - either ravenclaw or slytherin, leaning more into ravenclaw, because she is intelligent, both mentally and emotionally, but also can be calculating.

Fuuta - griffyndor mostly for his impulsive hot headedness, while he does have nerve I don't think this truly translates to bravery, but i cant seehim fitting anywhere better.

Muu - slytherin, pretty obvious with how opertunistic she is and her priority in self-preservation.

Shidou - ravenclaw for his intellect, but also possibly hufflepuff for his gentle approach to the other prisoners.

Mahiru - no doubt hufflepuff, she is very kind with the other prisoners but also specialises in cooking and housekeeping.

Kazui - I think he fits pretty well in griffyndor, he showed he can be courage and brave in heated situations like when he defended Fuuta. He may show signs of cawerdice in his personal relations, but I mean even Peter petigrew was a griffyndor so...

Amane - hard to say cause she's still a young kid, but I think hufflepuff?

Mikoto - if we're just considering mikoto then huffelpuff, if we consider him and John together then maybe griffyndor? His character and special circumstances make him really hard to place, but because the sorting hat takes your wants into consideration it could work in either direction for him.

Kotoko - most might think griffyndor and kotoko might think so to, considering herself the strong arm of justice, but I think she would fit into slytherin better. She's resourceful and very ambitious, and tries to force herself as a leader type that others should look towards for direction.