Life in the Uchiha household was quiet, almost solemn. Fugaku rarely spoke, and when he did, he was brief. That morning, he merely pointed toward the nearby forest.
"Practice. Focus on your feet."
That was all. Without further explanation, he was left there.
Itachi understood: if he wanted to progress, he would have to do it alone.
The tree before him seemed like an impossible wall. He placed a foot on the bark, released chakra from the sole of his foot… and immediately fell. He tried again, regulating the amount as if opening an invisible valve. Little by little, he learned the difference between too much flow (which made him bounce off) and too little (which made him slip).
Every mistake was a data point. Every fall, a discarded variable.
"This isn't about brute force… it's about balance," he murmured.
After dozens of attempts, he managed to climb over half a meter. When he finally reached the middle of the trunk, he stopped, panting. His small body was sweating, but his eyes shone. It was a successful experiment.
In the days that followed, he practiced on water as well. The contact with the liquid surface revealed a fascinating principle: chakra created a field of pressure that held him up.
It's a phenomenon of repulsion. Like a stabilized electromagnetic force.
That night, exhausted but unable to sleep, his mind jumped to another memory. Not from this world… but from the previous one.
A hazy memory of a show he had seen years ago, sitting in front of a screen. The blond protagonist of that anime performed a devastating spherical technique.
The Rasengan.
He hadn't been a superfan. But he remembered the general idea: a core of chakra rotating and compressing at the same time.
The concept fascinated him.
What would happen if I tried it now? Not as a ninja, but as a physicist. A self-stabilizing sphere, a mini-reactor in the palm of my hand.
He concentrated chakra in his hand. He molded it into an invisible sphere. He tried to spin it, forcing rotation while compressing it. At first, it was just an electric tingle. Then, a faint hum in the air. For a second, he thought he had it…
The sphere collapsed with a sharp pop, throwing him onto his back. The impact left him dazed, his hand burning and his chest heaving.
He started to laugh, breathless.
"It works… at least a little."
He hadn't achieved the Rasengan, not even close. But he had proven the idea was possible.
And for him, that was enough: a new experiment to perfect, a challenge that required method, patience, and more hypotheses.
In the darkness of his room, his fingers still trembling, he knew he had stumbled upon something that would obsess him for a long time.
Itachi extended his hand and concentrated chakra again. This time, he didn't rely on instinct, but followed a method he had decided on the night before.
Step one: rotation.
He imagined the sphere as a gyroscope, a tiny planet spinning in his palm. He channeled the chakra into a vortex, trying to make each current curve into a circle.
Step two: compression.
As it spun, he forced the chakra toward the center. Like a gas trapped in a pressure chamber. The air around his hand buzzed.
Step three: stabilization.
This was the hardest part. The chakra tended to disperse in an explosion.
It's like controlling a nuclear reactor without a containment vessel. I need a balance between outward thrust and inward collapse.
The sphere collapsed again with a dull snap. This time it didn't throw him back, but it left the skin of his hand red and stinging.
Itachi smiled.
"Partial progress."
Hours later, while resting in the shade, he remembered something he had read in the library: the elemental affinity of chakra. The Uchiha family mastered fire, but… what about him?
He needed to know.
He knew the method: a leaf. If his chakra was fire, the leaf would curl; if it was wind, it would split; if it was lightning, it would crumble; if it was water, it would moisten; if it was earth, it would turn to dust.
The problem was getting high-quality leaves for the test. He decided he would find a good batch at the clan market the next day.
Meanwhile, someone was watching him.
"You're Itachi, right?" The voice came from a nearby branch.
The boy looked up. A young man with dark hair and sharp eyes was watching him with a calm smile.
"I'm Shisui," the newcomer said, landing on the ground with feline grace.
Itachi recognized him. He was famous even among the adults: the genius of the Uchiha, the prodigy who mastered the Body Flicker Technique as if it were a game.
"You were doing something weird with your chakra," Shisui commented, tilting his head. "It didn't look like a clan jutsu."
Itachi evaluated him in silence.
Should I tell him? If I talk about gyroscopes and compression, he might not understand…
"It's an experiment," he finally replied. "I want to mold chakra in a new way."
Shisui's eyes shone with curiosity.
"An experiment? That sounds… different. Most people just repeat what they're taught."
Itachi felt something strange: for the first time since he woke up in this world, someone seemed willing to listen to him.
"Perhaps," he said, "we can figure out how chakra really works together."
Shisui smiled.
"I like how you think."
And so, under the golden light of the sunset, began the first conversation between two geniuses who would forever change the destiny of the Uchiha clan.
After their first conversation, Itachi remained alone under the tree, practicing the chakra control he had learned so far. With trembling hands, he tried to recreate the sphere of energy he had seen in his past life: a barely perceptible mini-Rasengan spinning in his palm.
Shisui watched from a distance, intrigued.
"That… what is it?" he asked.
Itachi, nervous but proud, raised his hand, showing the tiny sphere that spun for a few seconds before disintegrating.
"I call it the Rasengan… it's an experiment. I want to understand how to compress chakra and keep it stable."
Shisui approached, crossing his arms. A smile appeared on his face.
"Interesting. Not many kids think like that." He paused for a moment. "Look, I can teach you something that might complement that. Genjutsu. If you understand how to deceive perception, you could control not just the energy, but how others perceive it."
Itachi looked at him with bright eyes. His physicist's mind was already analyzing possibilities: If I can manipulate energy and perception simultaneously… I could create effects that are impossible to predict.
"Alright," he said finally. "I'll show you what I know about the Rasengan, and you teach me genjutsu."
Shisui nodded, satisfied.
"Deal. But don't expect shortcuts: it's all practice, precision, and concentration."
And so, the first exchange of knowledge between two geniuses was formed: Itachi with his "scientific" experiments, and Shisui with the traditional secrets of the Uchiha clan.