Next Chapter Theory

In short. Asa is dead. Again. But Yoru will sacrifice herself Pochita-style to ressurect Asa as a true hybrid.

So what's the evidence you say? There has been a lot of complaints on the Yoru focus in the last arc and the lack of Asa focus. From a writing point of view this makes a lot of sense if Yoru is about to die. We see her at her best and worst. As a monster but also as she conti he's to become more human. In the moment before she is struck we get the completion of her humanising arc. She rejects her goal in favor of her love. It's a completion. Asa on the other hand hasn't had the screen time to really justify her death at this point so I don't think we are losing her permanently. A final sacrifice by Yoru in a truly selfless fashion would also be a perfect capstone to her growth.

I think the blow to the head is lethal to Asa since we have never seen her regenerate and although she has some toughness her survivability feats aren't all that great. She also has half a brain so it's fitting if that is what gets destroyed to echo her first death.