Sasuke raised his hand, his fingertips reaching toward his left eye socket. He didn't even frown, and in a moment, he removed the Six-Tomoe Rinnegan from his eye socket.
Naruto received the Rinnegan with both hands and temporarily placed it on a tray lined with soft cloth, and then raised his hand to his own left eye.
His left eyeball detached completely from the socket, with the optic nerve bundle preserved intact. He quickly sealed his original left eye into a blank scroll, then picked up Sasuke's Six-Tomoe Rinnegan and placed it into his left eye socket.
The moment the Rinnegan entered his eye, Naruto's visual nerve endings connected with the Rinnegan's nerve bundles at an extremely fast speed.
Immediately after, all the basic abilities of the Rinnegan were clearly presented in his memory like an opened instruction manual.
Amenotejikara: instantly swap the spatial positions of two targets within a certain range.
Space-Time Teleportation: open cross-spatial channels for long-distance movement.
And the Six Paths abilities of the Rinnegan.
Then Naruto began to search for the deeper energy within the Rinnegan. Deep within the Rinnegan's ability structure, he quickly sensed two strands of power distinct from ordinary ocular power and Chakra.
One was extremely pure Yin Chakra.
One was the Sage of Six Paths's Yin Power.
Naruto guessed that the pure Yin Chakra was Indra's Chakra.
He immediately used Absolute Control to carefully peel off a small strand of Yin Power. Without affecting the overall structure and ocular power of Sasuke's Rinnegan, he guided this strand of Yin Power into his own body.
After the Yin Power left Sasuke's Rinnegan, it quickly began to dissipate, but Naruto was prepared for this. He used Absolute Control to lock it firmly within his body. Just containment wasn't enough, he also mobilized Kurama's Chakra to begin nourishing this strand of Yin Power.
Wrapped in Nine-Tails Chakra, the Yin Power finally stopped dissipating. It began to stabilize and started to multiply at an extremely minute speed.
Subsequently, he used the same method to guide Indra's Chakra into his body and nourished it with Kurama's Chakra
.
After doing all this, he left a memory in Sasuke's Rinnegan, as well as a Fuinjutsu.
This information was about what had happened during this period.
The Fuinjutsu was a protective barrier. If anyone attempted to forcibly seize Sasuke's Rinnegan, this seal would automatically activate.
After finishing all this, he removed Sasuke's Rinnegan from his eye socket and returned it.
Sasuke, who had been staring closely at Naruto's every move, immediately took the Rinnegan and pressed it back into his left eye socket. A pale green light lit up, beginning to restore the optic nerve connection.
A moment later, he opened his eyes, and the Rinnegan lit up with a faint purple shimmer under his bangs.
He quickly checked it. The ocular power was slightly less than before, but within an acceptable range. Then he noticed the added Fuinjutsu inside his left eye.
"Why did you add a Fuinjutsu to my Rinnegan?"
"Sasuke, although you are very strong now, it's not like you haven't been ambushed before. In case someone tries to steal or destroy your eye when you are not in a good state, this seal can help you once." Naruto said.
Sasuke was silent for a while, then thanked him, "Thank you."
"It should be me thanking you." Naruto shook his head.
...
Present.
Naruto picked up the test tube containing Sasuke's blood, and twirled it at his fingertips.
Then he extended his left hand, and split an incision in his palm. He poured the blood from the test tube into the incision, and the dark red blood beads were quickly absorbed into his body along the capillaries.
With a thought, the wound healed instantly, without even a scar left behind.
The genetic code in Sasuke's blood was clearly presented in his perception as if magnified by a microscope.
The Uchiha Clan's genetic sequence, Indra Chakra.
Naruto hurriedly used Kurama's Chakra to nourish these Indra Chakra strands together with the ones collected earlier. Although these Chakra strands were still weak, as long as they were in his body, they could slowly be nourished and become stronger.
After doing all this, he compared Sasuke's genetic code with the genetic sequence in his own body one by one. Because Indra and Asura originated from the same source, Sasuke's genetic code shared a large number of identical segments with his own.
He began to fuse the Uchiha sequence from Sasuke's genetic code with his own genes. As the genes were perfected, Naruto's whole body began to heat up. Compared to the violent reaction during the last fusion with Karin's genetic code, this fever was much milder.
Sasuke's genetic code mainly affected the ocular nervous system and changes in Chakra properties, with relatively limited impact on other parts of the body. Naturally, there wouldn't be a drastic change like the bone restructuring from last time.
After an unknown amount of time, the changes within his body gradually ceased.
Naruto seemed to sense something. He opened his eyes and took a scroll out of his ninja tool pouch.
Under Absolute Control, the pair of Shisui Mangekyo residing in his eye sockets detached and were resealed into the scroll.
Then, he used Absolute Control to begin restoring his own eyes. After completing the Uchiha gene, his eyes seemed to regrow and take shape. Soon, a pair of blue eyes appeared.
Naruto guided Chakra to the ocular pathways, following the awakening path of the Uchiha Clan obtained from the genetic memory in Sasuke's blood, and used Absolute Control to catalyze his own Sharingan Chakra.
Then, he slowly opened his eyes. The blue pupils turned scarlet in an instant, and a black tomoe emerged from the iris. Soon, a second tomoe followed, distributed symmetrically on both sides of the pupil.
The two tomoe began to rotate slowly in the pupil at first, then faster and faster. At the moment the rotation reached a certain critical point, a third tomoe emerged from the edge of the pupil.
Three-Tomoe Sharingan.
But the Three-Tomoe was only the starting point. Naruto had used Shisui's Mangekyo and had personally experienced Sasuke's Six-Tomoe Rinnegan, so he already had an extremely precise perception of Mangekyo-level ocular power.
He began to call upon his Chakra, catalyzing it according to the special Chakra frequency of the Mangekyo Sharingan. There was no need for emotional loss of control, Absolute Control acted directly on the Chakra.
Regulating the nature and density of every trace of Chakra, he converted ordinary Chakra into the special ocular power required for the Mangekyo Sharingan.
As the Mangekyo-level ocular power accumulated to a certain degree in the ocular pathways, the three tomoe in his eyes began to spin frantically at a speed far exceeding before.
Finally, the three tomoe fused together, turning into a hollow ring. Six jagged blades extended from the outer edge of the ring, evenly distributed around it, with each jagged blade presenting a perfectly symmetrical form.
A pair of Mangekyo Sharingan belonging to Naruto himself.
Naruto slowly closed his eyes, withdrawing the ocular power deep into his ocular pathways. When he opened his eyes again, his pupils had returned to blue.
Naruto raised his hand and touched his right eye. He felt this brand-new Mangekyo in his eye socket, which perfectly matched his own Chakra. It was completely different from the faint sense of estrangement when he had previously transplanted Shisui's eyes.
This pair of eyes grew from his own bloodline. Every optic nerve and every bit of ocular power was a part of his body.
Withdrawing his hand, Naruto recalled the characteristics of the Mangekyo Sharingan—Reflection of the Heart.
The Mangekyo gives birth to unique dōjutsu based on the wielder's deepest desires and obsessions.
Itachi wanted to change the fate of the clan and simultaneously craved power to end everything, awakening Amaterasu, which represents destruction, and Tsukuyomi, which represents control.
Shisui wanted to change the direction of the clan without bloodshed, awakening Kotoamatsukami, which could rewrite one's will.
After witnessing Rin's death, Obito completely closed off his heart, awakening Kamui that isolates everything outside.
After learning the truth about the clan annihilation, Sasuke wanted to inherit Itachi's power, awakening the same Amaterasu as Itachi.
"I wonder what dōjutsu my Mangekyo will awaken." Naruto muttered to himself.
He injected Chakra into his eyes and the Mangekyo pattern emerged in his pupils once more.
He tried to use his ocular power to perceive the abilities residing within, but the feedback he received was pure chaos. The dōjutsu was still gestating, just like a chick still in the eggshell. He could feel its heartbeat, but couldn't see its appearance clearly.
Naruto was not in a hurry. The Mangekyo's dōjutsu naturally require time to hatch. Some people's dōjutsu only manifest days after awakening, and some even need to experience a strong emotional shock to be fully activated.