Board Thread:Naruto Discussions/@comment-26993711-20160319001508/@comment-26773508-20160319064135

TheOneWhoLovesNaruto wrote: I just looked at it again, and there is no way that he used kamui. I know that much for sure. Then, on to speculation. I can not think of a way other than izanagi. Afterwards, he said that it was a good thing that Itachi didn't know everything about him, or else he would be dead. I don't know how that may translate into this, because Itachi knew about izanagi. If there was something else, I don't know what it could be. Itachi knew about Izanagi, but perhaps he didn't know that Obito could use it. But this sounds absurd, since Itachi was fooled into believing that Obito was actually Madara, and it sounds ridiculous for Itachi to believe that "Madara" couldn't use Izanagi.

Maybe Obito's actual secret was the collection of spare sharingans he had, so that he could spam Izanagi at least a hundred times. Perhaps Itachi believed that Obito possessed only one sharingan. I don't know. None of these speculations really fit well. But at least it should be obvious that Kamui isn't the secret Obito was talking about. Konan had it figured out. So would Itachi.