Considering its completely made up ..id say it works pretty well lol ...but yea its just one of those things , no use in going to deep into it...its kinda like asking how can they do clones lol
been watching alot of martial arts films recently from reason and wondering if there are any other anime based on it?,something like History's Strongest disciple or Tenjho tenge
as cool as a new main character would probably be, im more in favor of a time skip...that's if anything happens at all lol..could just continue from where it left of
lol it does makes sense if he loose all his power that he wont see dead people any more..but really want to see how the story continues:(..and it seems that to many people lost there arm lol but yama with one arm is still ultimate badass