Without hesitation, Kagami unsealed a storage scroll and retrieved Uchiha Itachi's Mangekyo Sharingan. Since he didn't know how to directly absorb yin energy from the eyes, he was forced to resort to the most direct, and most painful, method: replacing his eyes.
Steeling himself, Kagami gritted his teeth, reached up, and gouged out his now-useless eyeballs. He then quickly installed Itachi's Sharingan into the empty sockets. Immediately, he activated his Reversed Cursed Technique, rapidly connecting his optic nerves to the new eyes. Having performed a transplant before, he was familiar with the process and completed the gruesome procedure with practiced efficiency. Thanks to the powerful regenerative properties of his technique, there was no adaptation period needed. It was plug-and-play, with no risk of rejection.
As soon as the eyes were in place, Kagami felt a surge of pupil power completely distinct from his own. Under his conscious control, this new power from Itachi's Mangekyo began to flow toward his second, hidden pair of eyes. The two different energies slowly started to merge, beginning an unknown transformation. He knew that once this fusion was complete, he would likely awaken the Eternal Mangekyo Sharingan.
However, the process was a slow one. He estimated it would take about two months to complete naturally, or about one month if he actively focused on integrating the two powers. Kagami wasn't concerned. A month was a small price to pay, and he could afford to wait.
He opened his new eyes and immediately noticed a difference. His vision was sharper than before, and his reserves of yin energy felt slightly enhanced. He could also feel the presence of two new abilities within Itachi's Mangekyo: Amaterasu and Tsukuyomi. This was to be expected, as he now possessed Itachi's actual eyes.
However, Kagami could also feel that as his own eyes absorbed the power from his new ones, the vision in Itachi's Mangekyo was steadily degrading. Once all the power was absorbed, they would likely go blind. He felt no sense of loss. To him, Amaterasu and Tsukuyomi were mediocre abilities, far inferior to his own. Losing them was no great tragedy.
After ensuring the process was stable, Kagami concealed his second pair of eyes and stood, walking over to Madara. "You don't have much time left. Is there anything you wish to say?"
Madara heard him and shook his head slightly. "In this world, I have nothing left to worry about."
His lifelong obsession had been achieving peace through the Infinite Tsukuyomi. But now, he had let that go, choosing instead to entrust the future to his successor, Kagami. He knew that even if he could live, defeating Kagami was impossible, making his grand plan unattainable. Besides, if Kagami could bring true peace, the Infinite Tsukuyomi was no longer necessary. With Hashirama gone, his own motivation to live had vanished. He no longer felt any attachment to the world.
A faint, appreciative smile touched his lips as he looked at Kagami. "Boy, didn't you say you wanted me to do something for you? Tell me now, don't waste time. Hashirama and Izuna are waiting for me."
Looking at the legendary Uchiha, Kagami felt a pang of unexpected sadness. He had thought Madara would cling to his obsession until the very end. He never expected to hear such words of acceptance.
Kagami opened his mouth, about to ask Madara to summon the God Tree and activate the Infinite Tsukuyomi to resurrect Kaguya Otsutsuki. But then, a horrifying thought struck him. If Kaguya was resurrected in Madara's body, and he were to... sleep with Kaguya... wouldn't that be equivalent to sleeping with Uchiha Madara?
Even if Kaguya reverted to her original form, the vessel would still fundamentally be Madara's body. The thought of sharing a bed with a body that was once Uchiha Madara sent a visceral chill down Kagami's spine.
Furthermore, Kaguya's resurrection required an immense amount of chakra. In the original timeline, it was only possible by absorbing the chakra of everyone on the planet. But now, with the ninja world's population decimated, using the God Tree would likely drain every living being dry, turning the planet into a dead star. The world would be left with only him and Kaguya, and what would be the point of that? While he didn't particularly care for the lives of others, he didn't want to rule over an empty world.
After careful consideration, Kagami abandoned the idea. This didn't mean he had given up on resurrecting Kaguya, merely that he would find another way. He would wait until he was strong enough to break the moon's seal and release her true body. That way, there would be no psychological awkwardness and no mass extinction. With his system, he was confident he could achieve this eventually. This approach also had the added benefit of preserving Madara's Rinnegan, which he might be able to use in the future to evolve his own eyes. With Naruto and Hashirama gone, finding another source of Asura's chakra was impossible.
With his decision made, he changed the subject. "I want you to transfer control of the White Zetsu army to me," he said. "And also, teach me every jutsu you know."
White Zetsu? Madara thought, puzzled. What does he want with those things? Aside from intelligence gathering and being fodder for the Impure World Reincarnation, they were useless. But he was too weary to ask. He was about to die, so the question was pointless.
He nodded. "Very well. I will also teach you the method for creating them. As for the jutsu, I can simply transfer the knowledge with my Sharingan."
Kagami nodded in thanks, not bothering to explain. His reason was simple: he needed the Zetsu army to find Black Zetsu. If he wanted to reach the moon to free Kaguya, he couldn't do it alone. He suspected Black Zetsu knew a way. Although he hadn't seen the creature, he refused to believe it was dead. An ancient schemer like Black Zetsu wouldn't die so easily.
With Kagami's current power, Black Zetsu could no longer advance his "save mother" plan without going through him. Rather than letting the creature plot in the shadows, it was better to find and subdue him directly. Their goals aligned, after all. Black Zetsu might even end up calling him 'father' someday. As long as he wasn't a complete fool, he would cooperate. And if he refused? It didn't matter. Kagami could just as easily seal him away or destroy him.