"Shadow Clone: Release!"
Poof!
The two Shadow Clones stationed in the underground laboratory dispersed on command, dissolving into clouds of white smoke.
Toji slowly withdrew his gaze and began tallying today's gains.
As expected of himself.
Even as Shadow Clones, their research progress had not lagged behind the original body in the slightest. They had already achieved a breakthrough.
"Yin Seal."
He spoke softly and formed hand seals.
The next moment, a black diamond-shaped mark appeared at the base of his neck, like Ultraman's timer. The core for storing chakra had been completed and was slowly absorbing the physical energy that naturally leaked from his body.
All that remained was storing mental energy, then regulating the two and combining them into chakra. Once those steps were complete, he could officially begin stockpiling chakra.
He was one great step closer to truly rewriting the Yin Seal and making it his own.
This breakthrough was no longer some useless imitation. It possessed genuine energy-storage capabilities.
What did storing physical energy mean?
It meant that while Toji was awake during the day, he could continuously gather the physical energy leaking from his body. When fatigue set in at night, he could release that stored energy to restore his vigor whenever he wished.
He could directly remove sleep, a fundamental human instinct, from his daily routine.
Have you ever seen Konoha at four in the morning?
Toji probably would.
Greater stamina would also increase the amount of time he could use each day.
With the original body and Shadow Clones combined, while others had only twenty-four hours in a day, he had forty-eight, perhaps even seventy-two.
There was no way he could possibly use it all up.
Of course, maintaining such a near-perpetual state came with its price.
The research into the Yin Seal and Impure World Reincarnation, every single project was frantically draining his energy. The multiplied fatigue surged back like a tide, leaving him mentally exhausted.
Toji could clearly sense that the weakest heart in his body was on the verge of necrosis after being subjected to such constant high-intensity strain.
An ordinary Genin's heart had become a consumable for him.
It would never last until the day he died of old age.
No wonder ordinary shinobi did not dare use the Yin Seal. Without some special physique, Shadow Clones could genuinely kill you.
Shadow Clones were already like this. As for the more advanced Multiple Shadow Clone technique, perhaps only someone with as many stacked buffs as Naruto Uzumaki could use it freely in the entire Shinobi World.
However, Toji had anticipated this long ago.
Necrosis?
Then he would replace it.
Only after personally clearing away every trace of the underground laboratory did Toji return to the surface and lie back down on his bed.
He no longer needed to worry about physical energy, as the Yin Seal had already begun to work. But the depletion of mental energy was real. He still needed sleep to replenish that loss.
Besides, unless necessary, the human instincts and emotions rooted deep within him meant that Toji had never intended to completely abandon sleep, that brief respite which allowed both body and mind to empty themselves.
Tomorrow, he had to trick Uchiha Chiri...
He needed to restore his energy all the more.
Toji closed his eyes.
The following evening.
The setting sun dyed the stone slabs of the Uchiha Ninjutsu Training Ground a warm orange, while the evening breeze carried the faint scorched scent of Fire Release.
The corridor.
Uchiha Chiri rested her cheek on one hand, her elbow propped against her knee as the breeze gently stirred her purple hair.
She tilted her head at Toji beside her. "Today's Fire Release training is already over, Toji-kun. Did you come looking for me because there's something special?"
Based on their usual dynamic, Toji never sought her out outside of ninjutsu training or weekends, much less with such an unusual look on his face.
Toji fell silent for a moment. An expression called hesitation appeared on his face, a rare sight indeed.
He slowly said, "Yeah... there is something I need to tell you."
"I have a technique I intend to teach you, Chiri."
"A technique?"
The curiosity in Uchiha Chiri's eyes deepened. "What kind of technique? Could it be... Medical Ninjutsu?"
In her impression, all of Toji's ninjutsu and research had been related to medicine.
"Not Medical Ninjutsu. It's Sealing Jutsu." As he spoke, Toji solemnly pulled an ancient scroll from his robe and handed it to Chiri. "It is called the Yin Seal."
Yin Seal!!
Uchiha Chiri's pupils contracted.
As a legendary shinobi who had followed Madara Uchiha and Izuna Uchiha through the wars of the chaotic era, she naturally knew of the Yin Seal. She had experienced it firsthand.
It was the signature ninjutsu of Mito Uzumaki, the wife of Hashirama Senju, their old enemy, and an ultimate secret of the Uzumaki Clan.
She did not know its exact principles or full effects.
But she would never forget it.
Once, during battle, Mito Uzumaki had released her Yin Seal, unleashing an immense, almost terrifying flood of chakra. High-level ninjutsu had poured forth as though chakra were limitless, and the saturated barrage had completely suppressed Chiri, who had possessed only the Three-Tomoe Sharingan at the time, leaving her in a sorry state.
Because of that...
The Yin Seal had left an extremely deep impression on her.
"Toji-kun, where did you get this technique...?"
Chiri asked instinctively, but the moment the words left her mouth, she found the question absurd.
Her concern had muddled her thoughts, making her forget even such common sense.
Who besides Lady Mito Uzumaki could have given him a secret technique like the Yin Seal? It could not possibly have been stolen or taken by force. Even Madara Uchiha could never have done such a thing in the Senju Compound.
He would have been beaten senseless by the husband and wife together.
"Did Lady Mito give it to you?"
With a solemn expression, she extended both hands and accepted the scroll from him.
"Mm." Toji nodded faintly. "More precisely, the Hokage and Lady Mito decided together to give it to me."
"Then you..."
"You must have many questions. Before I answer them, look over the scroll first."
"All right."
Uchiha Chiri slowly unrolled the scroll across her knees.
The scroll was very long. To keep the end from falling onto the ground, she naturally laid its other end across Toji's lap and lowered her head to study it carefully.
The farther she read, the more astonished she became.
[Yin Seal: Used to accumulate and store chakra; can also preserve one's appearance and maintain youthful looks.]
She noticed the permanent youth effect first, and only afterward the function of storing chakra.
No woman could resist the temptation of preserving her appearance and delaying aging.
What was more, Chiri suddenly recalled Toji mentioning the Zenin Clan's naturally long-lived constitution to her before.
Thump, thump—
The air was so quiet it seemed almost frozen. She could even clearly hear her own racing heartbeat. The last time her emotions had churned so violently was when she awakened the Mangekyō Sharingan.
She thought of something, and at the same time realized that in order to read the scroll, she and Toji were sitting far too close together.
Her throat felt slightly dry as she softly said, "Toji, you..."
"Shh."
Toji raised a finger to his lips, his voice gentle and soft. "Every thought you have right now is correct, but please don't say it yet. The Yin Seal is very difficult to learn, and I don't want to put too much pressure on you."
After a pause, his low, magnetic voice slowly sounded beside her ear:
"Besides what you're thinking, I also need you to master it. Afterward, I'll conduct some experiments on you and help you completely cure your Bloodline Disease."
Chiri could no longer clearly hear what came after that.
That sentence kept echoing through her mind—Every thought you have is correct.
Before you continue