As the Nine-Tails' jinchūriki, Naruto was always in danger whenever he left the village. He was never allowed to travel alone — it was always in a team, usually with Kakashi, Yamato, or Kiyosuke accompanying him. Otherwise, he was confined to stay inside the village.
Since he was a child, Kiyosuke had always warned him: if no adults were around, he had to stay alert and never let his guard down.
Following that advice, Naruto quietly gathered what little chakra he had left, cloaking himself in darkness and leaving a shadow clone behind to sleep in his bed as a decoy.
All around him, the prison cells held countless ninja who had committed crimes.
These were shinobi who had failed missions for their villages or broken their village's laws. Once captured, they were sent here — to Hōzuki Castle. Those with true ability usually became rogue ninja instead.
People like Deidara and Sasori, for example.
Those imprisoned here had almost no chance of being released. When a few of them disappeared from time to time, no one in the Hidden Villages cared. Their lives meant nothing.
The air was filled with snores and occasional screams. Standing in the darkness with his arms folded, Kiyosuke glanced around and even recognized a few faces once featured on wanted posters. So they'd already been thrown into Hōzuki Castle, huh?
Among these people, aside from Naruto and a few others, most of them had long since crossed every moral line imaginable.
Kiyosuke didn't care much. In fact, he almost wanted to burn the entire place down just to save everyone the trouble.
Guards patrolled the corridors with strict precision. Even with the Heavenly Prison Technique maintaining control, there was still a minuscule chance that someone could escape — a rare possibility, but a possibility nonetheless.
The guards never slacked off, leading dogs as they patrolled.
When they passed by where Kiyosuke stood, the dogs suddenly began to growl and bark softly. Kiyosuke narrowed his eyes at them, and the dogs immediately tucked their tails between their legs in fear.
The guards were puzzled. In their eyes, there was nothing but darkness here — no presence, no figure, no chakra. So they dismissed it and hurried away with their dogs.
As they left, Kiyosuke sensed a chakra signature rapidly approaching. He turned his head, and from the shadows emerged a dark figure. The intruder crept to Naruto's cell and began unlocking it.
Click!
The sound jolted the shadow clone awake.
"Who's there?!"
Thud!
A sharp hand strike landed on the clone's neck, knocking it out instantly.
The intruder chuckled softly.
"Sleeping so soundly on your first night here? Should I call you brave or just stupid? This is Hōzuki Castle, kid."
He quickly blindfolded the clone, gagged it, then hoisted it over his shoulder and carried it away.
Moments later, the real Naruto appeared from the shadows. Seeing the figure leave, he sprinted out in the opposite direction.
That's right — he had expected someone to come after him, and decided to use the opportunity to stage his own escape.
Meanwhile, Kiyosuke followed the intruder silently, watching as the man carried Naruto's shadow clone around a corner and disappeared into the office of the castle warden, Mui.
Without making a sound, Kiyosuke slipped in behind them, activating Sage Mode. He used Object Transmutation and Concealment of Presence, transforming himself into a small, unremarkable pebble invisible to the human eye.
When he entered the room, it was empty.
"So there really is a hidden mechanism here, huh? This is going to be troublesome." Kiyosuke frowned. If there was a secret passage, forcing it open could expose him — and he wasn't ready to blow his cover yet.
"I'll figure it out later."
...
Suddenly —
Wooooo! Wooooo! Wooooo!
The alarms blared across the entire Hōzuki Castle.
The pitch-black halls instantly flared with blinding white light. Spotlights swept everywhere, dogs barked wildly, and the uproar woke every inmate from their sleep.
Seeing guards running back and forth, the prisoners quickly realized what was happening. Someone was attempting to escape.
It had been a long time since anyone dared try that here. Truly bold.
Kiyosuke dashed out. After several leaps and turns through the air, he spotted Naruto falling from the rooftop — unable to use chakra because the Heavenly Prison had activated. He crashed hard onto the ground, and moments later, several dogs surrounded him.
"This brat... caught already?" Kiyosuke shook his head. According to Hōzuki Castle's rules, an escape attempt meant solitary confinement — three days in the dark cell for the first offense.
He wrote everything he'd witnessed onto a scroll and sent it back to Konoha, stating that he would remain here for the time being.
Then he found a quiet spot to rest.
During the next three days, Kiyosuke thoroughly explored every corner of Hōzuki Castle. His favorite place, by far, was the kitchen.
The place was loaded with good stuff — plenty of meat, endless wine. No wonder the guards here were all a bit on the plump side, and the cooks were built like sumo wrestlers.
People often snuck food, so one more thief didn't matter. Pork knuckles, roast chicken, whole lambs — Kiyosuke helped himself to everything, sitting in the loft and feasting away. Hardly anyone came up here, so he didn't need to worry about being found. From there, he could even watch the prisoners in the yard below during their outdoor time. Not a bad view.
Chewing on a lamb leg, he peered down.
Mui was walking across the courtyard. Wherever he passed, the prisoners immediately stepped aside, creating a path.
Behind him, Naruto, freshly released from solitary confinement, blocked his way.
"Wait! I heard that defeating you can lift this technique! I'm challenging you!"
Pffft!
Naruto's voice was so loud that even Kiyosuke, still munching in the loft, heard it — and nearly spat out his food.
"Cough—cough— This stupid brat... really? He can barely use any chakra right now!"
Naruto's Uzumaki bloodline gave him immense chakra reserves, but the Heavenly Prison Technique sealed nearly all of it away. Any attempt to use chakra would cause unbearable burning pain through his body.
Just as Kiyosuke expected, Mui effortlessly defeated Naruto within seconds, leaving him bruised and beaten.
That earned Naruto another five days of solitary confinement.
"Sigh... did I teach this kid to be a reckless idiot?" Kiyosuke rubbed his forehead. "No, no, it's definitely not my fault."
He shook his head and muttered, "It must be Jiraiya-sama's teaching."
Yes — absolutely not his problem.
Five more days passed without any notable incidents. Deciding there was nothing left for him to do and that Naruto would be fine for now, Kiyosuke finally chose to leave.
But as soon as he returned to Konoha and entered the Hokage's office, he found Tsunade wearing her forehead protector and full battle gear, ready for war.
Not just her — Kakashi, Guy, Asuma, and all twelve of Konoha's young shinobi were gathered there. Even Kumogakure's Killer Bee and the Fourth Raikage were present.
"Whoa, whoa... what's going on today? Why are all the big names gathered here?" Kiyosuke asked with a grin.
Tsunade replied, "Perfect timing, Kiyosuke. We're about to launch an assault on Kusagakure!"
"What?!"