Fainting

The Substitution Technique had two targets: oneself and the object used to deceive the opponent's attention. The textbook clearly stated that it was the foundation of genjutsu. Whether it was true or not, he would believe it first.

So if he wanted to observe Yin Nature Transformation, this was the simplest technique he could use.

Shikaku had summarized Yin Release as the power to create form from the intangible.

Didn't the Transformation Jutsu, Clone Technique, and Shadow Clone all create things from nothing as well?

But the anime did not seem to classify them as Yin Release ninjutsu. Naruto, with his exceptionally pure Yang Release affinity, had used the Multiple Shadow Clone Jutsu from the beginning all the way to the end.

Or perhaps they were simply less difficult, with only a slightly higher Yin Release content.

Through the Sharingan, Sasuke could not clearly make out the power Shikaku used to control the smoke. Perhaps it was mixed with Chakra, or perhaps there was simply too little of it.

After all, the interference effect of the Substitution Technique was so weak that it was not even called genjutsu on its own.

He had a scroll of the Binding Jutsu (D).

He used sparrows and fish for experiments, trying to hold them in place.

It worked when he activated the Sharingan, but failed when he did not.

He really could not say he had learned the ninjutsu. He could only say that, thanks to the Sharingan, he could use it.

"I'm going to cast a technique on you. Once you see me finish my Hand Seals, try to see whether you can walk or raise your hand."

"Wait, Sasuke, wait. At least explain what kind of technique it is. I'm scared you'll suddenly hit me with a Great Fireball if you don't say anything."

Don't point a gun at someone without warning, was it? Then he would explain a little.

"I'm practicing genjutsu. It's a ninjutsu that temporarily restricts a person's movements. You don't need to do anything."

Hand Seals.

"Teach me later, too."

"Huh? Huh...?"

Naruto seemed to have been tied up by something. He could not move, but he did not feel any pain in his hands or feet as though he had been grabbed.

With the Sharingan, without the Sharingan.

Sure enough, he still needed to use proper genjutsu. After repeatedly trying it several times, he finally discovered something.

"Try breaking free from the genjutsu yourself. Disrupt your own Chakra."

"How do I disrupt it?"

The experiments were cast at a high frequency, while the observation window was very short—only during the moment the ninjutsu activated. Combined with the Sharingan and Shadow Clones, Sasuke was drained dry in half an hour.

Compared with Fire Style ninjutsu, genjutsu did not use Chakra as a bridge—or rather, it did not use Chakra in the same way Fire Style did as a bridge. It could take effect directly on Naruto from a distance.

When speaking of the Sharingan, the first thing that naturally came to mind was sight. And speaking of sight led him to think of all the other senses. If the senses worked, then naturally, other things could work too.

Though he was still not entirely certain, he now somewhat understood Yin Nature Transformation.

Yin Release could be understood separately as a new energy system. The Five Senses could replace the five basic Nature Transformations, while other possible unconventional methods could be understood as Yin-Yang Nature Transformations.

His "sight" was an innate "Nature Transformation."

Chakra concentrated in the brain and extended to the eyes, rather than expanding outward from the body like Fire Style.

Let's give it a try—Power of "I'm Thinking"!

Naruto struggled for quite a while. Sasuke did not know whether the genjutsu had worn off on its own or Naruto had broken free himself, but he could finally move again. "Hey, Sasuke, how about it? Teach me genjutsu later, okay~?"

If Naruto got annoying in the future, he could use genjutsu to make him shut up.

Sasuke's voice was somewhat weary. "Sure, but stop talking for now and move farther away. The hallway would be best. I need a windless environment."

Naruto moved away and watched eagerly. Facing a stick of incense, Sasuke stared at it intently.

The incense smoke swayed, began drifting in one direction, then curled back around...

Naruto could understand the smoke drifting in one direction, but the smoke moving on its own and curling into a circle was not right at all.

It worked!

He could not describe it precisely, but as long as he did this first, then that... it worked.

His Chakra was nearly depleted, so Sasuke dispelled his Shadow Clones to recover some Chakra.

With a poof, the Shadow Clone Sasuke vanished.

A tiny bit of Chakra returned.

With another poof, Sasuke toppled sideways straight onto the tatami.

Clang, clang, clang, clang...

The sound of metal containers falling to the floor came from the direction of the kitchen.

The smile on Sasuke's face before he collapsed, all the people who had died in Sasuke's home, the smoke moving around just now...

Naruto's hair stood on end in fright.

He checked Sasuke's breathing. He was not dead, but Naruto could not drag him.

With tears pooling in his eyes, he rushed out to find help.

Among their friends, the only one who seemed even remotely reliable was...

The sudden loss of consciousness. What a nostalgic feeling.

Someone was shaking him. Was he in a hospital? He wondered whether he would be late today...

Sasuke's eyes snapped open. He propped himself up with one hand. "My soup is simmering on the stove!"

"Relax, I already turned off the fire. Honestly, you were only gone for half a day, and you already got yourself into trouble."

It was Shikamaru.

"Thank you." Hearing that the stove had been taken care of, Sasuke immediately breathed a sigh of relief and lay back down.

Seeing no sign that Sasuke was about to faint again, Shikamaru asked,

"Naruto was rambling nonsense. Something about you not letting him move, then lighting incense, then collapsing, and saying your house was haunted. Do you know why you fainted?"

"Everything had been fine. I dispelled the Shadow Clones to recover Chakra, but the clones were exhausted too. I guess that was why I fainted. The after-effects of Shadow Clones are really strong. Hah."

"That was my guess. You train way too hard."

"I usually know my limits. Today, I just didn't account for the Shadow Clones being so exhausted too."

Shikaku came over from the kitchen carrying a cup.

"Drink it. Sleep for the day and you'll be fine. Your body is healthy; you're just mentally overworked."

The bitter taste entered his mouth, and an inexplicable cool sensation shot straight into his head. It did not feel like mint. It felt as though some icy Chakra had been poured over his head, while his stomach burned slightly.

"This medicine is amazing. Thank you, Sensei! It tastes pretty good, too."

Shikamaru seemed to recall something unpleasant. "That medicine is pure bitterness. Doesn't it make you sick?"

Naruto had already picked up the cup Sasuke had drunk from, intending to try a drop or two of the dregs.

The result was obvious.

"It's bitter, but it doesn't stink, and there's no weird aftertaste."

For Sasuke, who had loved coffee in his previous life, it was only a little more bitter than an espresso. Nothing he could not handle.

"I meant to teach you a lesson, but it looks like I'll have to adjust the formula next time." Shikaku's expression looked somewhat stern.

"Sorry, Sensei. I made everyone worry."

He answered sincerely, then Sasuke seized the chance to change the subject.

"Will drinking this keep me awake tonight? It feels like I drank coffee."

"No. The effects will probably fade in half an hour to an hour. It only soothes mental stress reactions. Afterward, you'll still feel tired."

"You're still young. You have plenty of time, so there's no need to rush your training. If you develop after-effects while you're young, they could stay with you for the rest of your life."

Sasuke could only repeatedly agree.