Board Thread:Rebirth: Applications/@comment-24019243-20140929212937/@comment-6003865-20141001133011

^I really don't have anything else to add to that. Making up a master to teach you a rare technique means he'd have had to learn it from the few people who knew it.

That being said you don't necessarily have to apply for Iruzen himself separately, it can be incorporated into the app how he had learned it.