To reach the Six Paths level, two aspects must meet the standard.
One is Yin Release—spiritual power.
Uchiha Madara, being the reincarnation of Indra, barely met the condition to awaken the Rinnegan only after obtaining the Eternal Mangekyō Sharingan. After that, the old man Madara bit off a piece of Hashirama's flesh to compensate for his lack of physical energy. This allowed him to satisfy the other condition, and it took him several decades to finally obtain the Rinnegan.
In terms of Yin Release and spiritual power, Yakumo was naturally not lacking. What she lacked was the body's Yang Release energy—and that was something Hikari could help her make up for.
Suddenly, the sun that had been suppressed by the moon appeared in the sky. Gradually it came to shine together with the moon, creating the rare sight of sun and moon coexisting in the heavens.
Hikari raised his hand.
Golden sunlight poured down onto Yakumo's body. Visible to the naked eye, her body gradually became full and complete.
Full in every sense of the word.
Originally Yakumo had been a teenage girl in the bloom of youth. But as the sunlight bathed her, her figure grew more graceful and alluring, her hair turned into a pure jet black, and two small, cute horns sprouted from her forehead.
"The simplest method to achieve the Six Paths is to use Yang Release energy to alter the body's genetic structure. First, endow Yakumo's body with Wood Release, which will allow her to better absorb Yang Release energy. Then, replicate the Uchiha genes. Guided by her immensely powerful spirit, the Sharingan will evolve rapidly—from the Tomoe Sharingan to the Mangekyō, and then to the Eternal Mangekyō."
"As for the final Rinnegan, it requires both spiritual power and physical energy to reach the threshold of the Six Paths. Only then can she complete the final catalyst."
Time passed minute by minute. Hikari worked on the procedure while Kaguya watched from the side.
*Gurgle...*
The sound of a growling stomach rang out. Only then did Obito realize that he had been watching all this time—at least twelve hours had passed, perhaps even more.
What surprised Obito was that he hadn't felt the passage of time at all.
'Did I get caught in a genjutsu?' Obito wondered to himself.
"It's not a genjutsu. It's because your body and spirit instinctively yearn for perfection. However, without external intervention, you would never be able to reach this level in your lifetime!" Hikari casually explained, having noticed Obito's confusion.
The reason for Obito's reaction wasn't due to poor self-control.
It was because human instinct, and the instinct of the spirit, both desire to become more perfect. The current Obito was just an ordinary person. He might not care about evolution, but his body and spirit betrayed his will—they wanted to evolve.
"I don't want to become a Six Paths. If possible, I only want to be with Rin." Obito suppressed the longing in his heart. His reason told him that even if he begged Kamizuki Hikari, he wouldn't help him.
Besides, his purpose for living all these years had been Rin. He wanted nothing else.
"I can help you with that."
"However, the shinobi world can no longer accommodate you. I will find a small world and exile you and Rin there."
For Obito's sake—and considering they had once been classmates—Hikari decided to grant him this final wish.
*Boom!*
A shockwave erupted from Yakumo's body, sending Obito flying backward.
The next moment, Yakumo opened her eyes.
A pair of deep blue Rinnegan appeared. Yakumo blinked instinctively.
"Hikari-senpai, what happened to me?"
Hikari said, "I helped you unlock the Six Paths genetic code. Now, you have reached the level of the Sage of Six Paths!"
Yakumo looked at her hands, then raised her head to gaze at the sky. She looked at the brilliant sun and the silvery moon, then gently waved her hand.
Instantly, the sun vanished, and the moon's radiance dimmed considerably.
Kaguya's expression changed. She looked up at the Divine Tree, feeling a surge of panic.
With just a wave of her hand, Yakumo had caused a ripple in the Infinite Tsukuyomi projected on the moon. This ripple might seem insignificant, but one must remember—this was just Yakumo waving her hand lightly.
If she were to exert her full power, could the Infinite Tsukuyomi even continue?
"So this is the Six Paths..."
Yakumo lowered her head, glanced at her now more perfect figure, and nodded slightly to herself.
"I feel that when I cast genjutsu now, it's much stronger than before. In the past, I could only affect things within a radius of a hundred miles. Now, not only can I project onto any location in the shinobi world through the moon, but I can also use genjutsu to turn illusion into reality."
"Like this!"
Yakumo waved her hand, and a figure from Obito's memory materialized before him.
At first, Rin was just a shadow. But as time passed, the shadow grew more and more real, finally becoming the twelve-year-old Nohara Rin.
"Rin!"
Obito rushed over frantically, embracing Nohara Rin tightly. However, the current Rin was merely an empty shell. Without a soul infused, she wouldn't even breathe.
"Please, help me revive Rin!" Obito pleaded, having realized this point.
If it were just Rin's shell, he had many ways to create it.
But what he wanted was the complete, whole Rin.
"What a pitiful existence."
"Originally, I wouldn't help you. But since Hikari-senpai has promised you, I'll lend a hand!" Yakumo thrust her right hand forward violently, tearing through space and entering an unknown dimension.
"What a troublesome old man!"
Yakumo muttered, then exerted force, pulling Nohara Rin's soul out from that space.
Obito was stunned.
He had imagined Rin might be revived, but he had never dreamed of a method like Yakumo's—directly extracting a soul from the Pure Land.
Wasn't there supposed to be a Shinigami in the Pure Land?
"I used to think genjutsu was about deception. But now I understand that the essence of genjutsu is using spiritual power to influence the world. For example, if I want to revive Nohara Rin, I use my spirit to alter the cognition of Rin's soul and the cognition of this body, allowing the soul and the flesh to match perfectly."
The next moment, Nohara Rin's soul was infused into the body. The shell began to breathe, its heart beat, and all other signs of life emerged.
"Thank you, thank you!" Obito held Rin as if she were the world's most precious treasure.
"Now, it's time for you to go. I've found a small world similar to the dwelling place of summoning beasts. You and Rin can live a peaceful life there."
Hikari couldn't be bothered to watch Obito's infatuated expression any longer. With a wave of his hand, a spatial fluctuation appeared, carrying Obito and Rin away until they vanished.
"Kaguya-sama... now it's your turn to choose."
"Will you choose to spare this shinobi world's chakra, or will you choose to fight the two of us for it?" Hikari politely gave Kaguya a choice.
No matter what she chose, Hikari wouldn't force her.
After all, he respected others' wishes the most. Hikari would absolutely not admit that his reason for wanting Kaguya to stay was to learn the secrets of the Ōtsutsuki clan.
In any case, he had plenty of time ahead. He could wait slowly in the days to come.