Despair Usami

Backstory
Usami used to be "Usami the Magical Girl" but after being assaulted by Monokuma and changed to look like him, she was named Monomi.

She eventually gets sick of everyone being so rude to her so she practically goes insane, and changes her look. She then teamed up with Monokuma to teach them the lesson they deserve. A lesson of Despair.

The students have tried to reason with Usami to come back on their side, but their reasonings so far have failed to bring her back

Chiaki Nanami
Chiaki is Usami's sister and who Usami works for, she gives Chiaki information on everyone and what they are doing. Chiaki is also Usami's sister as they were both made by Chihiro Fujisaki yet Chiaki got corrupted by the "virus" that Izuru implanted