The Phantom Dragon Nine Seals was an extremely powerful sealing technique, specifically used to seal powerful chakra entities such as Tailed Beasts.
However, such a powerful sealing technique could not be performed by a single person. The more powerful people there were performing it together, the less time it took. Back when Orochimaru was still in Akatsuki, ten of them had used this ninjutsu together.
Now that only nine remained, it required somewhat more time.
Thus, when Pain sensed that Ueno Kei and the others were rapidly approaching, someone had to go stall them for a while. The sealing was already at its final stage; as long as they delayed them for ten-odd minutes, it would be completely finished. After that, nothing would matter. As long as the sealing technique was not interrupted, everything would be fine.
That was why Itachi Uchiha stood in Ueno Kei's path, while Kisame Hoshigaki blocked Kakashi and the others.
But accidents always happened like this...
Ueno Kei frowned as he looked at the unidentified figure lying on the ground. That utterly unfamiliar face finally confirmed the doubt and sense of incongruity he had felt from the start.
Sure enough, the man before him was not Itachi Uchiha himself. It seemed to be some sort of forbidden technique that allowed part of Itachi Uchiha's consciousness to enter this person's body and control him, much like a puppeteer's methods. It really was ingenious. Ueno Kei sneered. It seemed that the Kisame Hoshigaki who had blocked Kakashi's group had likewise not been the real one.
Ueno Kei swiftly formed hand seals and released a fireball, cleanly and efficiently burning the corpse beneath his feet to ashes. He was far too familiar with methods of destroying evidence like this.
After Ueno Kei finished dealing with the traces here