Wait a second....

[Jim Rider]

Who said he had mastered it?

 

[StraawHat]

Loop Holes are awesome aren't they?

 

[Amaterasuice]

Loop hole to get the hokage's revived.



1. Hiruzen didn't show concern that he would fail in any way.......

2. Hiruzen was said to have known all jutsu in konoha, he would have knew about the mask... Cant question manga, sorry

He may have known all jutsu in Konoha, but that doesn't mean he knows every mask of Uzumaki.

 

[Edo Odin]

Loop hole to get the hokage's revived.



1. Hiruzen didn't show concern that he would fail in any way.......

2. Hiruzen was said to have known all jutsu in konoha, he would have knew about the mask... Cant question manga, sorry

1. That's what I said, even if he knew about the masks, he wouldn't have shown any worries, which he didn't

2. Jeez, let me break this down for you. Sure, he may know all the jutsu, but it doesn't mean that he knows the whole story of each jutsu. Does he know for sure who created the Doton Wall Jutsu ? Or the Great Fireball ? No, not necessarily, he just knows how to use htm.