The Book of Sealing

In the middle of the wooden cabin, Shuoyue and his student Obito solemnly unrolled the scroll.

The Book of Sealing contained countless forbidden techniques and ninjutsu developed by the Second, Tobirama Senju. It was a true treasure. That was precisely why Konoha had kept it sealed for generations.

Deep within the quiet shrine, time seemed to have lost all meaning. Only the changing seasons outside the window marked its passage.

The enormous scroll of the Book of Sealing slowly unfurled across the altar. It was densely covered with countless forbidden techniques and secrets that Konoha had collected, developed, and sealed away since the village's founding. Uchiha Shuoyue and Uchiha Obito—present as a chakra consciousness—sat facing each other. They had temporarily removed their masks, and four Sharingan eyes, each holding different powers and experiences, focused on this treasure trove of knowledge and abyss of taboos.

At first, their research progressed so smoothly it was almost frightening. The power of the Eighty Gods Mirror was nothing short of heaven-defying. Shuoyue's eyes were like the most efficient scanners and decoding devices. Under their supreme powers of insight and analysis, the core principles and chakra patterns of complex, obscure techniques and secret arts requiring specific bloodlines or harsh conditions were peeled apart, understood, and imprinted layer by layer.

He tried copying his first A-rank ninjutsu—the Shadow Clone Technique. The process went unexpectedly smoothly. The light of the Eighty Gods Mirror flowed, and in almost an instant, it had analyzed and reconstructed the technique. Shuoyue formed Hand Seals, chakra surged—Poof! A clone identical to him appeared beside him. Success.

Obito watched quietly from the side, his white mask resting on his lap. A flicker of admiration passed through his exposed eye, but it was overshadowed by a deep scrutiny. He knew that power had never come so cheaply.

However, as they explored deeper into the Book of Sealing, venturing into its more forbidden sections, problems gradually began to emerge.

When they tried to copy an S-rank genjutsu that involved an extreme application of Yin Release, Shuoyue clearly felt his chakra consumption increase exponentially! It wasn't just the amount; the very quality of his chakra was being drained, as though the dōjutsu were forcibly wringing energy from the depths of his soul to complete the process of "reflection" and "reconstruction"!

In the end, the genjutsu took shape, though only with difficulty. Shuoyue's face had paled, and fine beads of sweat had formed on his forehead.

"It seems copying comes at a price," Obito said calmly. "The more powerful a technique is, and the closer it comes to the source of the rules, the heavier the burden on its user. Your Eighty Gods Mirror is more like a bridge connecting 'understanding' and 'realization,' but you still have to pay the 'cost' of crossing it yourself."

Shuoyue nodded silently. A grave look flashed in his deep purple eyes, which had yet to awaken. He had felt the limitations behind this power.

The real challenge came when they first attempted to copy a fragment of an extremely ancient and dangerous dōjutsu recorded at the end of the Book of Sealing.

It was a forbidden dōjutsu involving the tearing of space. The records were incomplete, and its principles were obscure and difficult to understand.

Shuoyue pushed the Eighty Gods Mirror to its limits. The intricate patterns in his eyes spun faster than ever as he tried to analyze the broken symbols and distorted flows of chakra. He could feel an immense amount of chakra being frantically drained from him, even reaching toward something deeper—perhaps his life force, perhaps some fundamental part of his soul.

However, at the very instant the dōjutsu's model was about to finish forming in his eyes—

Buzz!

A sharp, intensely unstable pain suddenly shot from deep within his eyes! It felt as though the mirror were about to shatter!

The dōjutsu model under construction instantly warped and destabilized. Then, like shattered glass, it exploded in his "field of vision" and vanished without a trace!

The copy... had failed.

A powerful backlash surged back along the channel connecting him to the dōjutsu. Shuoyue groaned and staggered, his vision going black as a wave of nausea rose within him. His eyes felt as if they had been burned, stinging fiercely, while his once-abundant chakra instantly dwindled.

Even stranger, he could clearly sense that all his "understanding" and the "model" of the shattered dōjutsu remained in the Eighty Gods Mirror's "records." Yet an invisible "barrier" prevented him from trying to construct or use it again. It was as if he had used up his "allotment" for the day.

Obito immediately stepped forward and placed a hand on Shuoyue's back. A gentle but immense flow of chakra slowly entered him, helping him recover from the backlash and steady his disturbed breathing.

"So it failed..." Obito mused. "It seems that even the Eighty Gods Mirror can't completely defy certain rules. Copying powerful abilities, especially dōjutsu, comes with an inherent 'failure rate.' And it seems that a failed technique gets 'locked' for the rest of the day, making another attempt impossible."

Over the following year of intensive research and countless attempts, they gradually figured out the patterns and limitations of the Eighty Gods Mirror's copying ability:

1. Exceptionally high chakra consumption: Copying ninjutsu or dōjutsu consumed far more chakra than learning and performing the technique normally. The cost increased exponentially with the technique's rank, complexity, and the depth of the rules it involved. Copying an S-rank technique or a forbidden art could drain more than half of Shuoyue's chakra in a single attempt, sometimes requiring Obito to help him recover.

2. An inherent failure rate: No matter how thoroughly they prepared or analyzed a technique, the act of copying with the Eighty Gods Mirror had a fundamental, unavoidable chance of failure. After extensive testing, they confirmed that the rate remained steady at around forty percent. Failures seemed somewhat random: sometimes a simple A-rank technique failed, while an exceptionally difficult S-rank technique occasionally succeeded on the first try.

3. A penalty for failure: Whenever a copying attempt failed, the model of that ninjutsu or dōjutsu entered a "dormant" or "disordered" state for the rest of the day, making another attempt impossible. They had to wait at least a day for the Eighty Gods Mirror to settle that "disorder" before trying again. This did not mean the second attempt would certainly succeed; the failure rate still applied.

4. Dōjutsu faced especially strict limitations: Copying dōjutsu generally consumed more chakra and had a higher failure rate than copying ninjutsu of the same rank. The risks were particularly high for Mangekyo-level dōjutsu that required a specific bloodline or extreme emotions to activate.

That year brought a rapid increase in power, but it was also a year of constantly testing the limits, suffering backlash, and deeply understanding the price of power.

Shuoyue mastered many of the forbidden techniques and secret arts in the Book of Sealing, reaching a level of strength almost beyond comprehension. But he also grew quieter, his presence more restrained and dangerous, like a volcano held in check. Every failed copy and every bout of weakness after his chakra was drained made him more keenly aware that the Eighty Gods Mirror wasn't an all-powerful divine treasure. It was a double-edged sword—extraordinarily sharp, yet just as capable of cutting its wielder.

Obito remained at his side throughout, guiding him, standing guard, and offering reminders. He watched Shuoyue charge down the path of power, worried that he might be consumed by it, but understanding that it was the path Shuoyue had chosen for himself, one from which there was no turning back.

"All power comes at a price, Shuoyue," Obito once warned him after one of his failed attempts left him utterly exhausted. "The Eighty Gods Mirror has given you the 'possibility' of reaching every answer, but whether you can obtain those answers, and how many, still depends on the size and strength of your own 'vessel.' Don't lose sight of your true self amid the countless things reflected in this 'mirror.'"

Shuoyue merely wiped away the thin streak of blood at the corner of his eye, brought on by the backlash. His black eyes were unfathomably deep.

He knew the price. He was willing to pay it. As long as this power could help him cut through every fog and obstacle ahead and complete that final... reckoning. A year's accumulation was enough. The next step of his plan was gradually taking shape in his mind.

As things stood, the sheer range of Shuoyue's dōjutsu alone was almost equivalent to that of a squad made up entirely of special jonin.

First were the two dōjutsu he knew best and wielded most proficiently: Dōjutsu: Kamui and Dōjutsu: Amaterasu.

Next came his basic but powerful dōjutsu.

Dōjutsu: Tsukuyomi, an immensely powerful genjutsu.

Dōjutsu: Kagutsuchi, which allowed him to manipulate the form of Amaterasu's flames.

And finally, his greatest trump card. It had taken him a full month to copy this most powerful control-type dōjutsu: Dōjutsu: Kotoamatsukami!

After putting away the Book of Sealing, Shuoyue sat cross-legged on the roof, silently practicing the Hand Seals for the Summoning Technique.

This night was destined to pass quietly, without incident. Yet the countless nights like this would give rise to a truly terrifying monster.