Naruto shrugged his shoulders, and the two Chakra Arms made identical movements. The fingers curled, as if grasping something in the empty air.
He chose to start with the innermost stone wall of the cave. The stone wall made almost no sound, leaving only a patch of fine cracks where the golden fingers had penetrated.
He controlled the depth and angle of insertion, distributing the force evenly across the entire palm, and then applied a slight amount of power. A massive boulder was steadily pulled out by the Chakra Arm.
"I used too much force, the resistance when inserting was much smaller than expected."
Naruto muttered to himself, noting the operational feel.
At the same time, he controlled the Chakra Arm to gently lower the rock to the ground.
The speed of excavating the second rock was noticeably faster. From insertion to grabbing to putting it down, the Chakra Arm performed the action in one smooth motion, taking less than ten seconds in total.
For the third block, he used only the right hand.
For the fourth, he switched to the left hand.
By the fifth, he began trying to work continuously by alternating between his left and right hands. While the right hand dug out a block and moved it away, the left hand was already digging out the next one.
Naruto wasn't just crudely hollowing out a hole, he was expanding it without compromising the mountain's overall structure. With every block he excavated, he would glance at the surrounding rock strata patterns to ensure the support structure remained intact.
Soon, just two Chakra Arms were no longer enough to satisfy Naruto. He expanded the condensation points of his Chakra from his shoulders to other parts of his back, manifesting seven or eight Chakra Arms at once to work simultaneously.
Chipping, grabbing, moving, transporting, and setting down—he established a streamlined assembly line.
The cave's area rapidly expanded in complete silence.
The massive amount of Chakra granted to him by Kurama Chakra Mode and the fine manipulation abilities brought by Absolute Control combined perfectly in this engineering-like training.
When the first hint of dawn began to break in the eastern sky, Naruto stopped his work. Standing at the entrance of the cave, he looked at the fruits of his night's labor.
A domed cavern about five hundred meters in diameter was fully presented before him. The ceiling of the cave was high enough that he couldn't touch it even if he jumped, and the ground had been repeatedly leveled by Chakra Arms.
On the rock walls, he had left several rock protrusions on purpose, which could be used to hang ninja tools or carve sealing formulas in the future.
Next was setting up the Sensory Suppression Barrier.
He selected a core node in the center of the newly excavated cavern, and then created two clones to stand at the cave entrance and the cave ceiling respectively. The three barrier hand signs were completed simultaneously within seconds.
Now, the interior of this cavern, just like the fifty-meter-diameter training clearing outside, was firmly enveloped by the Sensory Suppression Barrier.
Walking out of the waterfall, Naruto noticed that the pile of rocks he had excavated had piled up into a small mountain.
Originally, he thought he could just pile these stones by the river, but looking at them now, the quantity was too vast. Let alone a ninja, even ordinary villagers passing by would find it suspicious.
Leaving them as they were was definitely not an option. If they were discovered, it would be equivalent to directly telling Konoha that someone had undertaken a massive project here.
And he didn't know any Earth Release Ninjutsu yet, so he had no way to fuse these rocks back into the mountain or sink them underground.
"Then I can only destroy them all." Naruto muttered to himself.
He raised his right hand, and a Rasengan rapidly formed in his palm. Then, he walked up to the nearest rock and pressed the Rasengan against it.
The moment the rapidly spinning Chakra sphere came into contact with the rock, the rock's surface was shaved and shattered in chunks. The debris was ground into fine powder within the spinning Chakra and evaporated in the high temperature generated by the friction.
A massive boulder over ten meters high was shaved from top to bottom by the Rasengan in less than half a minute.
After destroying several large rocks in a row, Naruto looked down at the spinning Rasengan in his hand, and a sudden thought popped into his mind.
'What if I throw the Rasengan?'
The Rasengan's biggest shortcoming for a long time had been that it required close-range contact to deal damage. If he could turn it into a long-range attack, his combat flexibility would go up a level.
Without hesitation, he decided to try it. Naruto formed another Rasengan. This time, instead of holding it in his palm to press it against something, he made a throwing motion and flung the rapidly spinning Chakra sphere toward the pool.
The moment the Rasengan left his palm, it flew forward normally in the air for seven or eight meters. Naruto almost thought he had succeeded.
But just as he was about to record the feeling, the blue Chakra sphere slowed down more and more. The edges of the sphere began to blur, and the Chakra dissipated in all directions. When it flew to about twelve or thirteen meters, it completely disintegrated into a blue mist, falling onto the pool and stirring up a negligible ripple.
"As expected, it doesn't work."
Naruto withdrew his hand, feeling neither disappointed nor surprised.
***
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