Re: solving of breaking the mask of tobi 100% spoiler
The theory about Kagami Uchiha being Tobi has been around for quite some time, since the subtle connection can be noticed very easily. I was among the first people to point out the fact that Kagami was not present with the other elders during the nine-tails attack on Konoha, most people did not notice that, so I give you credit for that.
However, you have pointed out some additional info that makes good sense. Thinking back, the statement about Madara and Danzo last seeing eachother at the uchiha massacre would hold water when used in correlation with your theory. If Kagami was missing during the attack on Konoha, then its very possible he was working with Danzo at that point and later in the uchiha massacre. It also makes sense that Kagami would be most familiar with the last generation of Konoha shinobi, as you pointed out, much more sense than Uchiha Madara who had been away from the village for so long.
The only question I can ask, is why then did Itachi believe Tobi was in fact Madara? He referred to Madara as the only other Uchiha that obtained MS. So wouldn't that mean that Kagami never achieved it? I guess its possible that Kagami is Tobi and never had the MS himself, but it is all very confusing. I mean Itachi was certain that Tobi was Madara. Perhaps when it comes down to it, Kagami is the current 'Madara' but I'm certain that the original Madara still has a part to play in all this, beyond just being in Kabuto's 6th coffin. Good work though. Now I'm gonna catch up on the other responses on this topic...lol