Momo is a dangerous sociopath that was sent for rehabilitation(or just finding a place to keep her at bay) at a mental institute because she was convicted of two murders.

Mina is a volunteer at that particular institute, and she is always very calm, no matter the circumstances. 

What will unfold after Momo meets Mina?

Sociopath: Lacks conscience because they do not care, feels a limited range of human emotions because they are plagued by emotional abnormalities and they would do anything to get whatever they want.

Will update once I'm done writing out the full story!