Why would he need to write on his body when its already there.Sai gives Danzo his ink pen, he writes his final seal on his body and then activates Izanagi.
Proceeds to stun either one of them and then use the last seal to kill them both, but wait. Izanagi. And he returns to his state prior to death, which has the seal on him!
Because he set that one to specifically go off at a point when his body was failing him. Obviously to a point beyond what Izanagi can go to, or Izanagi goes off too quickly before that. Otherwise I wouldn't know why he wouldn't make use of this technique more.Why would he need to write on his body when its already there.
It suppose to set if off before he died but the manga showed Danzo deciding to do it earlier. That means he can choose when to activate at will too.Because he set that one to specifically go off at a point when his body was failing him. Obviously to a point beyond what Izanagi can go to, or Izanagi goes off too quickly before that. Otherwise I wouldn't know why he wouldn't make use of this technique more.