Arai's training for Yubi had never been limited to simple sparring.
He taught through ambushes, deception, exhaustion, and pressure. Their mission on the border was not only to stop infiltrators from Amegakure, but also to inspect caravans crossing the region, watch the canyon routes, and judge danger before it appeared. Arai turned every one of those duties into part of Yubi's education.
Sometimes, while Yubi was inspecting a merchant convoy, Arai would suddenly use the Transformation Technique, disguising himself as a trader, a porter, or even a frightened civilian before launching a surprise attack. Other times, he would take on the appearance of a Rain ninja and strike from a blind spot, forcing Yubi to react without hesitation. On worse days, he planted traps in the valley ahead of time and waited to see whether Yubi could detect them before stepping into disaster.
He did all of it for the same reason.
Battles between shinobi were never simple. Fighting styles varied too much, tricks changed too quickly, and the battlefield was full of feints nested inside deadlier feints. Arai wanted Yubi to build real instinct—the kind that could keep a person alive when there was no time left to think.
Because of that brutal training, Yubi returned to base every day covered in dust, grit, and blood.
Sometimes the blood was not his.
More often, at least lately, it was.
There were even days when he was so drained that Arai had to carry him back to the canyon base himself. That sight did not escape Sasori's eyes. The red-haired boy saw everything, including the fact that even after being dragged back half-conscious, Yubi would still find a way to practice in secret when everyone else believed he was asleep.
He was like a lunatic squeezing every last drop out of his own body.
Under that harsh, varied training, Yubi's growth was obvious.
His body grew stronger. His reactions sharpened. Most importantly, in close combat he was no longer the same child who could be put down in an instant. He could now exchange several moves with Arai and hold his ground for a short while instead of being cleanly overwhelmed from the start.
That rate of improvement was shocking even to an elite jonin like Arai.
In his eyes, Yubi was like a dried sponge dropped into water. Whatever experience or technique Arai showed him, the boy absorbed it at once. Not only that—he digested it, refined it, and began using it almost immediately. Sometimes Arai barely had to explain a point before Yubi had already grasped it.
His comprehension bordered on the monstrous.
Two months passed in a blur.
During that time, aside from training, they also ran into scattered enemies from time to time. Most of them were shinobi from Amegakure. The large battle had ended bitterly for the Rain Village, but Sunagakure and Amegakure had not made peace. Small-scale clashes still broke out along the border, and the hostility between the two sides never truly cooled.
After watching Yubi for long enough, Arai finally decided the time had come.
So he changed the training plan.
He was no longer satisfied with letting Yubi sharpen himself in familiar ground. He chose instead to bring both Yubi and Sasori across the border and launch a strike into a Rain Village stronghold.
Courtesy demanded repayment.
Since the people of Amegakure insisted on causing trouble in the Land of Wind, then Sunagakure would return the favor in kind.
Whoosh, whoosh, whoosh—
Late one night, three figures—one tall and two small—cut through the darkness and headed straight toward the border between the Land of Wind and the Land of Rain.
As they ran, Arai spoke in a low, steady voice. "This will be treated as an independent field mission. I will record the entire operation and submit it to the village after we return. I won't interfere unless absolutely necessary. What the two of you need to do is simple—kill Amegakure shinobi as quickly as possible, then escape without getting yourselves killed."
"Understood," Yubi said at once.
He knew exactly who that warning was aimed at.
Sasori had completed far more missions than he had. No matter how young he was, the difference in actual field experience could not be ignored.
Arai continued, his expression grave. "Based on your previous encounters, I need to remind you of one thing. The Rain shinobi you fought before were not especially strong. Amegakure may not be counted among the great villages, but it was one of the most active forces in the recent war, and Hanzo the Salamander is no ordinary leader. The people who survived that battlefield and are still guarding the border are all dangerous."
His gaze swept over the two boys.
"Once we cross into the Land of Rain, finding their hidden positions is only half the job. The other half is concealing yourselves. If you expose your movements too early, the mission becomes a death sentence."
Yubi nodded again.
The border drew closer with every leap.
Under cover of the night, the gravel underfoot gradually gave way to darker, softer earth. Tufts of green vegetation began to appear in the wilderness, scattered at first and then in clusters. Farther off, black mountain silhouettes rose against the sky. Even without anyone saying it, the change in terrain made it clear that they were approaching one of the routes where the Land of Wind met the Land of Rain.
As soon as they neared the line, hidden Sunagakure sentries emerged from the dark and moved to stop them.
That lasted only until they recognized Arai.
"Arai-sama."
The two Sand shinobi bowed immediately.
Arai slowed only slightly. "How is it here?"
"Yuyin has been quiet lately," one of them answered. "There've been a few small movements, but we've detected all of them in advance. Nothing major so far."
"Good."
The guards' eyes drifted to Yubi and Sasori.
They knew Sasori by sight. The other child was unfamiliar.
One of them could not help asking, "Arai-sama, these two are...?"
"I'm taking them out to gain some experience," Arai replied casually.
The two border shinobi exchanged glances.
Even with Arai leading the way, slipping alone into enemy territory was dangerous enough to make seasoned men uneasy. Sasori being there made sense; everyone in Sunagakure knew the Chiyo family's genius puppeteer. But the black-haired boy beside him looked too young, too ordinary at a glance, too much like a child who should not be anywhere near a mission like this.
Still, no one questioned Arai's judgment aloud.
After a few more quiet words, he led Yubi and Sasori past the cordon and deeper into the Land of Rain.
Behind them, one of the border shinobi watched the retreating figures and muttered, "Do you know that other kid?"
"Never seen him before," the other answered.
Ahead, the night thickened.
"The border is definitely tighter than the rear," Yubi thought as he ran. "We were noticed the moment we showed ourselves."
From that point on, Arai's attitude sharpened even further.
"Be careful," he said. "Stay close and don't fall behind."
The instant the words left his mouth, his speed increased.
He clearly had prior knowledge of Amegakure's border layout. Every route he chose, every turn he took, and every patch of shadow he used felt deliberate. He avoided open ground, kept them away from obvious patrol paths, and slipped them through the terrain as if he had memorized it long ago.
Sparse trees began to appear around them.
Soon after, a wide forest spread out ahead like a black sea.
Without pausing in the slightest, all three figures leaped into it and began using the trunks as cover, vaulting forward at full speed.
Only moments after they passed, several shapes emerged from the darkness behind them.
One of the Rain shinobi narrowed his eyes and scanned the ground. "I thought I heard something. Was it the enemy?"
Another crouched, checked the earth, then the nearby brush, then the low branches overhead.
After several breaths, he shook his head.
"No traces of intrusion."
The suspicion passed.
The figures vanished again.
A few hundred meters away, in the shadowed side of several massive trunks, Arai, Yubi, and Sasori crouched low to the ground, using the darkness and roots for cover.
No one spoke.
This was enemy territory now. Even the smallest unnecessary sound could expose them.
After a moment, Arai lifted one hand and gave a quiet signal.
Then he slipped into a deeper band of shadow and disappeared.
The meaning could not have been clearer.
From here on, the task belonged to Yubi and Sasori.
Naturally, Sasori had no intention of working together with Yubi.
Arai had made the nature of the mission plain from the beginning. This was not only an infiltration mission—it was also a contest. Whoever killed more enemies, whoever performed better under real combat conditions, whoever proved more capable in the Land of Rain would be the winner.
That meant one thing.
From this point forward, the two of them would be hunting separately.
Sasori turned his head and looked at Yubi.
His expression remained as cold and indifferent as ever, but there was an unmistakable edge of provocation in his eyes. It was the silent challenge of someone who had no doubt he would win.
Then, without a word, he chose a direction and moved.
In the blink of an eye, his small figure dissolved into darkness between the trees.
Yubi watched him go and could not help smiling.
"Seriously..."
But the lazy curve of his mouth faded quickly.
His eyes sharpened.
The softness vanished.
The moment his feet touched the damp forest soil of the Land of Rain, the mood inside him changed completely. The months of brutal training, the life-and-death experience in the canyon, the battlefield medical work, the constant tension, the knowledge he had stored away about this world, and the ambition he kept buried deep inside his chest—all of it quietly aligned in that instant.
This was not a drill.
Not a lesson.
Not a spar.
This was a true hunt.
And unlike the scattered fights he had faced before, this time he had come to enemy territory by choice.
He adjusted the grip on the scalpel hidden in his hand and slowed his breathing.
The air here was different from the Land of Wind.
It was wetter, heavier, carrying the scent of soil, leaves, and the faint threat of rain. The darkness beneath the forest canopy was also deeper than desert shadow. Every trunk could conceal an ambush. Every patch of brush could hide a tripwire, a body, or a waiting blade.
That should have made the place more dangerous.
Instead, it made Yubi calmer.
Because danger left patterns.
And patterns could be read.
He lowered his body, controlled the sound of his steps, and let his gaze move over the shapes of the ground, the tension in the branches, and the tiny disturbances that most people would have ignored. Somewhere ahead, there were Rain shinobi hidden in this forest, convinced that the night and their territory belonged to them.
Yubi's lips curved once more—this time without humor.
His hunt...
Was beginning.