User blog comment:Xilinoc/Ch. 640 - BABY,HOLD YOUR HAND 3 (Mad Lullaby no.7)/@comment-5657895-20150827133130

I wonder if this is the same Nemu from the very start of the series then, or if that one had died in between arcs?

Nah, it most likely is the same Nemu, and her shared experiences with Uryuu and the others have changed her.

I kind of thought Pernida was silly when it was revealed to be a giant arm, but it is incredibly tough, and this fight is pretty good.