The term Bunkai to my understanding does not actually mean what people think it does. Bunkai means to have a conversion. However in the martial arts world this conversation is an analysis or breakdown of the movement in a Kata or Hyung.
There are traditional breakdowns and there are also Kyusho Jitsu / Pressure Point breakdowns. Sometime these will overlap and other times they will not. This is an indepth and lifetime study.