Inside Orochimaru's laboratory, Ye Uchiha's eyes successfully evolved into the eternal Mangekyō Sharingan after he received a transplant of Mangekyō Sharingan cloned from his own.
At last, he no longer had to worry about going blind from overusing his ocular power. Feeling the abundant power brimming within his eyes, Ye Uchiha looked exhilarated.
Seeing that Ye Uchiha's transplant had succeeded, Orochimaru nodded slightly and licked the corner of his mouth with his long, scarlet tongue. "The cloning experiment for the eternal Mangekyō Sharingan was a success. We can now fuse the eternal eyes without transplanting a close relative's Mangekyō Sharingan. Would you like to try evolving them into the Rinnegan now?"
Touching his eye sockets, Ye Uchiha asked uneasily, "Are there any risks?"
"The surgery has over a ninety percent chance of success. That pair of Rinnegan you brought back was extremely valuable for research. Kabuto and I have more or less finished unraveling their secrets."
His amber, slit-pupiled eyes swept over the mismatched red and gold Rinnegan resting in the cultivation tank, and a feverish flush spread across Orochimaru's face.
"The ultimate evolved form of the Sharingan is the Rinnegan. There are two conditions for that evolution: the Uchiha Clan's eternal Mangekyō Sharingan and the Senju Clan's Wood Release sage body. In addition, you need the chakra of Indra and Asura, the sons of the Sage of Six Paths."
"Indra and Asura, the ancestors of the Uchiha and Senju, were both children of the Sage of Six Paths. One inherited the sage eye, while the other inherited the sage body. Only by combining those two powers can the Rinnegan be born.
"Thanks to the information Kabuto and I have gathered over the years, along with the chakra you provided from Asura's and Indra's reincarnations, we finally obtained the key