Hm, now that that
Naoto Naoi guy(?) is loose without anyone to stop him, the afterlife is going to be one hell of a war-torn place. Neither SSS nor Naoi will stop before the other is dead. Since they are already dead, the best bet will be putting them in an
And I Must Scream situation, i.e. trapping them inside miles upon miles of concrete. And even then, it's not a permanent solution.