Board Thread:Versus Debates/@comment-26636534-20170822151908/@comment-734582-20170825153700

Hungry Ghost realm wrote: Sharingan can see through things and if you didnt know itachi read the uchiha tablet and researched the uchiha and senju history. He knows madara doesnt have space-time ninjutsu which is true and he has seen obito using space-time ie; kamui. Sharingan doesn't literally see through things, it doesn't have X-ray vision. Obito also used the excuse that he was severely weakened by the Valley of the End to explain the power discrepancy. Something he mentioned to Itachi, since Itachi complains to Sasuke that (fake)Madara has grown weak and isn't fit to lead the Uchiha.

Besides, Itachi was not aware that Obito had a spacetime ninjutsu. He never demonstrated that power to Itachi. When he used that power next to Sasuke, he didn't notice it was a space-time ninjutsu. Kakashi didn't even know Obito's phasing was a teleportation until much later and he had MS to observe it with. Obito never used the portal next to Itachi. And the databooks made it clear that he used Kamui to escape the Transcript: Amaterasu, something Obito referred to as a secret he kept from Itachi.