Yamori will change his mind.
As it reaches the end of the year, Yamori would take time to really meditate on his goal and realize that being a vampire was something he didn't want because he spending time and enjoying the night with Nazuna (a like-minded person) was enough.Of course, that would then make the council deem him a liability, leading to Nazuna making him her offspring anyway since Yamori had come to love her, or the system being completely rewritten.
