The plan has been decided. Compared to Uzumaki Naruto, who has little understanding of spiritual power, Uchiha Sasuke, who is good at illusion, is more familiar with battles in the spiritual space.

After all the preparations were made, Hatake Kakashi remained on the sidelines to prevent any accidents from happening, while Uchiha Sasuke carefully sat down in the small pool of the Falls of Truth, and then radiated his chakra and perception outwards.

After a while, Uchiha Sasuke, with his eyes closed, was wondering why there was no response yet. Suddenly, he felt something in his heart, and then he opened his eyes and looked at the waterfall of reality in front of him, which was exactly the same as before.

“It has already started!”

Silently and imperceptibly, people fall into the spiritual world. The waterfall of reality is indeed worthy of its name.

Although the scenery is exactly the same as the outside world, the surroundings are no longer the real environment. Instead, they are replaced by a spiritual space without people noticing.

As time goes by, the ninjas caught in the Waterfall of Truth will fall deeper and deeper, and eventually, the fundamental evil obsession deep in their hearts will be completely mobilized.

"It's been so long, it should be about time..."

Although Uchiha Sasuke, who possesses the eternal Mangekyō Sharingan, is able to resist for a while, if he uses all his strength, if he is not deeply involved, he may be able to completely break the spiritual space created by the Waterfall of Truth.

But Uchiha Sasuke, who wanted to let it go, just waited for some unexpected events to slowly happen around him.

The originally sunny sky became dark and gloomy, and the faint gray mist seemed to cover the scenery in a layer of gauze, making people feel a little unreal.

Just as Uchiha Sasuke was waiting, the water of the waterfall suddenly twisted, and a Sasuke with dark skin, lightning sword wings flashing behind him, and two long swords in his hands, one red and one white, slowly walked out.

"Sorry to have kept you waiting. It's not easy to show up once in a while!"

This is the strongest fighting posture before the Mangekyō Sharingan opens. The dark side of Uchiha Sasuke appears in the spiritual space in this form.

Uchiha Sasuke frowned, looking at this familiar face.

"Was I ever this ugly?"

His hair had turned into an embarrassing lead-gray color, and his skin had become even darker. His face was distorted by the burst of power, and he didn't look like a kind boy at all.

Even the lightning sword wings that showed a sense of power still gave people a terrifying sense of threat.

The dark side of Sasuke holding the sword in both hands is so different from his true self that the weird feeling can't be shaken off.

"So, you overestimate yourself... No, it's me!"

Originally the two were one. The power of the Waterfall of Truth itself was not strong, but it could lure the ninja who fell into it, splitting their hearts into two opposing parts, which then restrained and influenced each other.

The strength of the incarnation of the dark side opposite Uchiha Sasuke does not depend on how powerful the Waterfall of Truth is, but on whether his own reason can suppress the desires hidden deep in his heart.

"You really don't know what you're talking about!"

The Mangekyō Sharingan in Uchiha Sasuke's left eye instantly appeared, and where his sight was focused, a ball of dark flame suddenly rose up, enveloping it in an instant, and after a moment, it was burned to ashes.

"How dare you boast with such little strength?"

“Really?”

A strange voice suddenly appeared from the side and behind. Uchiha Sasuke was shocked and quickly dodged, but a big cut was still made on his right arm.

"How is it possible to be unscathed?"

Although it is a spiritual space, the simulated Amaterasu Black Flame is still lethal. This is the terrifying thing about spiritual warfare. If the damage to the mind is strong enough, it can be directly fed back to the body through chakra. If you are completely destroyed here, you are very likely to die.

"It seems that you still haven't figured out the nature of the Falls of Truth!"

Using the speed advantage of the Lightning Sword Wings, he suppressed Uchiha Sasuke's dark side incarnation while attacking and laughing.

"Your enemy is not the Waterfall of Truth, but yourself. If you cannot find the true reason for my birth and eradicate it, I will never be destroyed here, unless you die with me!"

"So troublesome?"

Uchiha Sasuke was fighting and thinking at the same time. After a moment, he looked up and looked at the incarnation of the dark side that was leaving a long afterimage.

"It seems that the ninjutsu duel and the battle are just a means to delay time and make me get deeper into trouble, so that I can't take care of other things. If I ask, what will happen if I fail?"

"Hahaha... Of course, 'we' are still safe, but as for the outcome, you don't know whether you will be the one controlling your body's will in the future."

"How is this possible? This is clearly just a trial, there shouldn't be such danger!"

"Danger, no, I think you're mistaken..."

Sasuke's dark side incarnate showed a wicked smile.

"You are Uchiha Sasuke, but Uchiha Sasuke is not you. Even if you disappear, it will not affect the existence of Uchiha Sasuke as an individual..."

"Are you saying that you will replace me in the future?"

"Replace? I don't like that word!"

Sasuke's dark side incarnation slowed down the pace of his attacks slightly.

"In fact, we are one, just two incompatible points of divergence. Normally, I would not show influence over will, but now, I can exist independently. Although it is not complete yet, it will be soon."

For the first time, Uchiha Sasuke felt a little regretful about his motive for rashly entering the Waterfall of Truth. It was really a bit reckless.

"If I can't hold on, will I be invaded by the twisted will? How deep the impact will be depends on my awareness!"

At the same time, Uchiha Sasuke began to have some doubts about the true effect of the Waterfall of Truth.

"If you are not a ninja who is extremely proficient in spiritual power, I am afraid you will not understand so much. People who are not sensitive to Yin Dun can't understand the true effect of it. What should this ability be called?"

"Who knows... However, some monks who pretend to be gods seem to know these things, baptism, inspiration, etc., probably like this. If it is an evil god, it is called enchantment, corruption, etc. The terms used in the secular world are easier to understand. I think brainwashing is the most appropriate term."

"Brainwashing yourself with your true inner desires? What a disgusting way of saying it!"

Knowing his current situation, Uchiha Sasuke felt relieved. The unknown is the most frightening and uncontrollable, but difficulties are the whetstone for tempering oneself.