It's not imprisonment; it's going undercover.

In every nation and shinobi village, whenever a ninja commits a grave crime in violation of their principles, they are sent to Hozuki Castle. The warden there is a master of sealing techniques, able to implant chakra-restraining chains into the bodies of offending shinobi, suppressing their ability to gather chakra and rendering them no different from ordinary people, unable to use any jutsu. In this way, the prison maintains brutal control and subjugation over its inmates.

Moreover, should a prisoner attempt to escape, the sealing formula within their body transforms into burning chains of fire, incinerating them alive. Since its construction, Hozuki Castle Prison has been highly regarded. No matter how notorious the criminal, once sent there, they are said to be reformed completely. It is, for all intents and purposes, a place of no return—much like the legendary underworld.

Throughout this, the Pufferfish Demon closely observed Kisame’s reaction. After hearing his sentence, Kisame was far calmer than anticipated. Impressive. The Pufferfish Demon nodded slightly, assured he had not misjudged the man. His tone softened as he continued speaking to Kisame:

“Kisame Hoshigaki, do not despair just yet. Remember, you are now a member of the Hidden Mist’s Black Ops, my subordinate. I am sending you to Hozuki Castle, not as a prisoner, but as an undercover operative.”

Undercover?

“I await your orders, sir,” Kisame replied, feigning an attentive posture.

“I have recently received confidential information,” the Pufferfish Demon explained. “According to this intelligence, an inexplicable civil conflict has erupted in the Hidden Sand Village. Amidst the chaos, the Scorch Release shinobi Pakura—who once killed our own Kurosuki Raiga, Kurisame Karuwari, and Munashi Jinpachi—has committed a capital crime and is being sent to Hozuki Castle Prison. Your mission is to infiltrate the prison and eliminate Pakura, ridding the Hidden Mist of this enemy.”

Civil unrest in the Hidden Sand, Pakura imprisoned?

Upon hearing this, Kisame could surmise that the Third Kazekage had likely gone missing. To be precise, the strongest Kazekage in history had been secretly assassinated by the sixteen-year-old puppet master Sasori of the Red Sand, plunging the Hidden Sand into a leaderless turmoil. The strife there was, no doubt, another struggle for power, not unlike recent events in the Hidden Mist.

Kisame had once thought he could change Pakura’s fate; now he saw he had, but only for the worse—she had been sent straight to prison. Clearly, she must have fallen out bitterly with the rest of the Hidden Sand.

Returning to the mission at hand: on the surface, sending a newly promoted Chunin into Hozuki Castle as a criminal—whether as an inmate or an assassin targeting an elite enemy Jonin—was no different from sending him to his death.

But if Kisame refused, there was no need to send him to prison; he’d be executed on the spot.

“Do you have any questions about this mission?” the Pufferfish Demon asked, tapping the armrest of his chair.

“I will obey your command and carry out the mission with my life,” Kisame replied firmly, bowing low.

His acceptance was not a stalling tactic, nor was it out of any intent to save Pakura. Rather—

He suddenly remembered something kept in Hozuki Castle Prison.

Compared to that, even the great blade Samehada—the ninja sword most suited for him—seemed utterly unremarkable in his eyes at this moment.

“Good. As expected of the man I have chosen.” The Pufferfish Demon nodded in satisfaction and clapped his hands. Several Black Ops shinobi materialized, approaching Kisame with shackles in hand.

Clearly, this was a setup from the start; fortunately, Kisame had not acted rashly.

He extended his hands without protest, allowed himself to be shackled, and was escorted away.

He would be held in a temporary cell in the Hidden Mist, then at dawn, sent out of the village to Hozuki Castle Prison.

Watching Kisame’s departure, the Pufferfish Demon secretly breathed a sigh of relief. He truly admired Kisame—especially now, when talented manpower was in short supply and the need for young prodigies to cultivate as trusted aides was great.

Even if the Fuji family demanded accountability, there were ways to protect Kisame if he so wished.

Yet, after reviewing Kisame’s career, he noticed that this man, for all his merits, had an uncanny effect on his superiors. All of Kisame’s past commanding officers had, for one reason or another, met untimely ends—it was truly unsettling. After much thought, the Pufferfish Demon decided he could not keep such an unlucky individual by his side and came up with this solution: send Kisame to Hozuki Castle Prison.

Night fell, and the moon hung cold and clear.

Pale moonlight filtered through the small window into the Hidden Mist’s temporary prison cell. Outside, Black Ops shinobi patrolled the corridors, ensuring strict security.

Inside, Kisame Hoshigaki—now classified as a dangerous criminal—was confined.

Anyone else, trapped in such dire circumstances, would surely be in despair. But Kisame’s heart was brimming with excitement. He almost wished he could sprout wings and fly straight to Hozuki Castle Prison.

Because within those walls was something he desired above all else.

It was called the Box of Ultimate Bliss.

According to legend, this was a ninja tool once wielded by the Sage of Six Paths himself. It was said that, in the Sage’s era, the Grass Village used the Box of Ultimate Bliss to wage war time and again, nearly conquering the entire world.

From what Kisame understood, the Box of Ultimate Bliss, being the ultimate weapon of the Sage’s era, had, over the ages, devoured the negative emotions of countless souls, eventually giving birth to a monster known as "Satori."

This box lived and moved with Satori, and would end with Satori as well. Satori could not only read minds but was also incredibly powerful. In the original story, even the likes of Gamabunta, upon seeing Satori, immediately fled with Naruto without a second thought.

To challenge Satori head-on was simply impossible.

In the end, Satori was only weakened after being moved by Naruto’s words and was then defeated through the combined efforts of Naruto and his allies, before being sealed beneath the sea by Killer Bee, the Eight-Tails Jinchuriki, together with the Box of Ultimate Bliss.

“The Box of Ultimate Bliss…” Kisame murmured those words.

The ninja tools he had absorbed thus far had indeed made him much stronger. At thirteen, he already possessed abilities comparable to advanced bloodline limits, and was strong enough to rival the leader of a village.

But in truth, on the level of his very being, he had not undergone a fundamental transformation.

Even if he absorbed a hundred Seven Ninja Swords or mastered a hundred bloodline limits or A-rank jutsu, it would be meaningless. When facing the likes of Hashirama Senju or Madara Uchiha, with their world-shattering power, he would still be annihilated instantly.

Kisame realized:

After reaching Kage level, every step towards the higher realms of "Super Kage," the summit of the ninja world, or even the realm of the Sage of Six Paths, was a monumental bottleneck.

He now stood before such a barrier.

Thus, Kisame desperately needed to devour an unprecedentedly powerful ninja tool to break through to a higher level of existence.

A tool of the Sage’s level was the best choice.

Among such legendary ninja tools, there were only a handful in the entire world, and the Box of Ultimate Bliss was second to none.

If Kisame could obtain the Box of Ultimate Bliss and absorb it, transforming into a being like Satori, he would instantly become one of the most formidable forces in the ninja world.

Therefore, he had no choice but to go to Hozuki Castle Prison.