"You made a version of a chakra test seal that doesn't seem to react to mimicry though."
"Up until those keyed in are dead. Then it resets entirely and lets anyone in."
Not that that's actually a real problem:
Door 1: Naruto, Hinata, etc.
Door 2: Those keyed in to Door 1, plus the Hokage, Sarutobi, Hiashi, possibly a couple of other people trusted by both the Hokage and Naruto.
Door 3: Those keyed in to Door 2, plus an even larger number of people trusted by both the Hokage an Naruto, the primary criterion being they want to **** Danzo up the ****. (What? You thought Sarutobi couldn't be vengeful?!)
Similar vaults can be constructed for other clans with different people keyed in.
before he was fully bound to the Kyuubi. Then you factor in the Shadow Clone training method and the sheer number of clones he uses daily and it's really no wonder that he's so good at infiltration along with practically anything else he touches. in terms of cumulative experience levels for the subjects he's trained in he's likely SS tier at minimum.
Better. Much better.
I've got a partly written story (okay, 189 words of story, and 8835 words of outline, including the seven words I just added ("Stealth/infiltration training for Naruto with seals")) which involves abusing shadow clones to their limit _without_ adding artificial limitations. Hint: if mental stress transfers, so does mental relaxation.
I hope to actually write it this year.
Let's see... 1, 2 and 9 are dead outright. 3 and 8 were well on their way recently, and now, just a year after 1 and 2 were executed, 7 and presumably 4 are showing signs of dying. How long do 5 and 6 have at this point? Six months? A year?
Zetsu better get his affairs in order; it seems his time is running out.
At this point in time, as I understand it, it doesn't matter what Zetsu does. He might be able to start a war, but that's it. He's already dead, he just doesn't realize it yet.