I got just THE idea
how about "friendly fire" do just as much damage as regular attacks
this way we can kill our team in the beginning and have to care about only 4 enemies left instead of 8

if there is friendly fire in the game, why just half backed? it staggers you, so you are open to enemy attacks, but does not make enough damage to kill you (well except you have some stupid raider, shugoki, lawbringer or nobushi in team who perform 3 heavy attacks in a row).