Seeing this, Hawking chuckled. He made no move to stop them, instead taking out a bottle he had prepared long ago and placing the Rinnegan inside.
His goal had always been just one Rinnegan, because he still needed to keep one of his own eyes to look at the moon.
There were two necessary conditions for a Saiyan to undergo the Great Ape Transformation. One was naturally a tail, while the other was using their eyes to see a full moon and receive Blutz Waves.
If both eyes were replaced with Rinnegan, there was no telling whether he could still receive Blutz Waves and transform into a Great Ape.
For him, giving up the tenfold boost in Combat Power from the Great Ape Transformation just for the Rinnegan's power would be putting the cart before the horse.
Two Rinnegan could certainly increase his Eye Power and greatly enhance the power of ninjutsu, but he did not rely on Rinnegan ninjutsu in battle. What he wanted were the Rinnegan's abilities to read memories and revive people.
What he needed was the Rinnegan wielder's trait of automatically mastering all Chakra nature transformations, allowing him to quickly learn most ninjutsu.
As the eyes of the Sage of Six Paths, the Rinnegan were difficult for anyone without an Ōtsutsuki Clan body to control. Nagato was the perfect example.
Rather than greedily taking both Rinnegan and increasing the burden on his body, he might as well use just one. With his physical constitution, even without being an Ōtsutsuki, he could easily bear one Rinnegan with virtually no burden at all.
That was only one reason. On the other hand, if he took both Rinnegan, Obito and Zetsu would be completely unable to continue their plans.
Without the Rinnegan, they would be unable to create the