Suddenly sensing that Nagato's Rinnegan might help him increase his strength, Uchiha Tsuki narrowed his eyes slightly and agreed to follow Nagato, Konan, and the others on their mission. However, as Uchiha Tsuki followed Konan and Nagato out of that secret base, he continuously used the Uzumaki Clan's special sensory ability to probe the chakra fluctuations within Nagato, hoping to discover what was unique about Nagato's Rinnegan.
The uniqueness he meant was naturally not the Rinnegan's Six Paths abilities, but rather how Nagato's Rinnegan could help Uchiha Tsuki improve his strength. Based on his knowledge of the original story, Uchiha Tsuki had long known that Nagato was an ordinary member of the Uzumaki Clan. The reason Nagato possessed Rinnegan like the Sage of Six Paths was entirely because Uchiha Madara had bestowed them upon him. Thus, those Rinnegan had never belonged to Nagato in the first place—they belonged to their original owner, Uchiha Madara.
Then, as Uchiha Tsuki used the Uzumaki Clan Secret Technique to sense the unusual chakra fluctuations within Nagato's body, along with the power of those Rinnegan...
At last, Uchiha Tsuki understood what made those Rinnegan special to him!
"That's right. Those Rinnegan are just like in the original story—they're Uchiha Madara's eyes!"
"And since I, who crossed over into the ninja world, am also Uchiha Madara's descendant, if I take Uchiha Madara's Rinnegan and fuse them into my Eternal Mangekyō Sharingan, it may very well cause a new mutation in my Eternal Mangekyō Sharingan."
"Perhaps after I absorb those Rinnegan, even my Purple Eye might evolve once again!"
"I never imagined that my inexplicable decision to join Akatsuki back then would lead me to a new path for increasing my strength."
"But how am I supposed to take Nagato's eyes?"
"With my current strength, it seems