Kakashi sat under a tall tree near the forest's edge, a shaded spot where the sun filtered through the leaves in patches of gold. His eyes followed the movements of his students with quiet focus.
Sasuke was practicing his lightning transformation. Sparks of electricity jumped from his fingertips into the soil, burning small trails into the earth.
Naruto, farther down the field, was yelling at a stubborn leaf, trying to slice it in half using wind chakra. And Sakura sat cross-legged by a small pond, guiding thin streams of water through the air with delicate precision.
Birdsong echoed through the trees. A gentle wind carried the scent of pine and damp earth. It was a peaceful day on the surface, but Kakashi's thoughts were far from idle.
He reached into his pouch and unrolled a small sealing scroll. Next, he pulled out a thin brush, a vial of ink, and a blank tag. His chakra flared gently as he dipped the brush and began to draw.
"I can use my Formula Reconstruction to build this seal piece by piece," Kakashi murmured, mostly to himself.
With a smooth motion, he traced a spiral in the center of the tag. That spiral would act as the core of the seal, the part that would draw in ambient chakra from the air or, in battle, from enemies.
Then he added three concentric rings around the spiral, each filled with precise, miniature symbols etched in flowing calligraphy.
"The first ring absorbs outside chakra… the second filters and automatically refines it, like mixing physical and spiritual energy," Kakashi said quietly, talking himself through the process. "And the third ring releases it, slow and steady."
He paused, observing how the chakra flowed through the design. It was drawing in chakra too quickly. That kind of intake could overload a person, causing spiritual backlash or even unconsciousness.
With a few careful strokes, he adjusted the spacing in the third ring, slowing the flow of chakra to a steady trickle.
"Better," he said.
The tag began to glow faintly. Kakashi placed his hand on it. A soft pulse of chakra moved up through his fingers, gentle, purified, and clean. There was no pain. No resistance. Just pure, usable chakra.
A small, contented smile crept onto his lips.
"Sealing Art: Chakra Refinement Seal," he named it, setting the brush aside.
He spent the next two days refining it, testing it, and applying small versions of the seal to inert tags and discarded kunai. By the second day, he had embedded a working version directly onto the back of his left hand, hidden beneath the cloth of his glove.
It worked better than expected.
"It can gather chakra from fallen enemies, or even from nature itself… and convert it into my own," Kakashi noted, pleased. "It even accelerates chakra recovery during rest."
In the distance, his students trained with tireless energy. Naruto was shouting again, clearly beefing with the leaf. Sasuke had managed to shape lightning into a narrow arc that buzzed near his palm. Sakura bent a ribbon of water into a perfect ring and hovered it above her shoulder like a crown.
Kakashi closed his eyes, letting the sound of their effort fill the air around him.
He hadn't told them about the seal yet.
They weren't ready, not until it was fully tested, not until he was sure it wouldn't harm them. But when the time came… he would pass it on. Probably.
…
Later that afternoon, with the sun beginning to dip, Kakashi stood alone on a ridge just beyond the training field. The light breeze ruffled his hair as he looked down at his own body.
Beneath his shirt, a second seal pulsed softly against his skin.
Kakashi placed his hand flat over his stomach. The flesh beneath warmed faintly, and with a simple hand sign, the seal revealed itself.
A glowing pattern emerged, a circular design that resembled a spiral sun, surrounded by five tiny elemental marks. Each represented a different chakra nature. Today, the wind mark glowed faintly.
He was using it to test something new: storing elemental chakra over time.
The wind picked up, swirling through the trees. Kakashi released a trace amount of wind-natured chakra into the air. The seal responded. A soft pull began. The mark on his abdomen absorbed it, refining and storing the energy inside.
"It's working," he murmured, his voice light with restrained satisfaction.
He released the technique. The seal dimmed and faded, vanishing beneath his skin like a whisper.
The chakra remained sealed safely inside, dormant but ready for use.
"This seal… it could change a lot," he thought.
In long, drawn-out battles, chakra conservation was everything. If this technique could absorb natural or ambient chakra slowly over time, and safely store it, then Kakashi could dramatically extend his combat potential, maybe even reach levels similar to a Jinchūriki under the right conditions.
He exhaled slowly, relaxing his shoulders.
This was just the beginning.
He turned his gaze toward his students again and called out:
"Come here, all three of you."
Naruto stopped mid-shout, Sasuke looked up, and Sakura lowered her hands gently from her waterwork. The three of them jogged over quickly, sweat on their brows, but their spirits high.
"I want to test something," Kakashi said, tugging off his left glove.
On the back of his hand, the Chakra Refinement Seal glowed faintly beneath the skin.
"Naruto," Kakashi said, "I need your help."
Naruto blinked. "Me? Uh… what're we testing?"
"Just stand still. And trust me," Kakashi said with a half-smile.
Naruto nodded, though his brow furrowed in confusion.
Kakashi formed a single hand sign. Lines of light suddenly lit up across his arm, stretching from the base of his wrist all the way up to his shoulder. They pulsed like veins of glowing chakra.
"Whoa!" Naruto exclaimed. "What is that?!"
"Focus," Kakashi said gently. He stepped forward and pressed his glowing palm against Naruto's stomach, right over the seal that housed the Nine-Tails.
Inside Naruto's subconscious, the fox stirred.
It felt the foreign chakra touch. Not aggressive, but invasive.
"What is this?" the Nine-Tails growled. "You dare steal my chakra, human?"
Naruto's body shuddered slightly. He looked down, wide-eyed. "Sensei… I feel something weird. Is it… is it the Demon fox?"
"No need to panic," Kakashi said.
His expression turned serious. He formed another hand seal, then tapped Naruto's stomach again with two fingers. A stronger, deeper glow surged through the seal, just for an instant.
Inside the seal, the Nine-Tails recoiled as if struck. The pull of its chakra stopped instantly, and new barriers of reinforced chakra formed around it, further restricting its influence.
Naruto gasped. "What was that?"
Kakashi stepped back. "I just strengthened your seal."
"You… used a sealing technique on me?" Naruto asked, rubbing his stomach.
"Only a supportive one," Kakashi replied. "It reinforces the seal's structure and helps prevent the Nine-Tails from disturbing your chakra flow during training."
Naruto's eyebrows lifted. "Wait… so you can actually mess with seals like that? Even the one on me?"
"Of course," Kakashi said, as if it were obvious.
'That's why I didn't do it before. The Third Hokage monitored Naruto. But now, with the situation out here… It's time I took a more direct role.' Kakashi thought.
Naruto stood there, stunned, but also impressed. "That's kinda awesome…"
"It's more than awesome," Sakura said, looking at Kakashi's glowing arm in awe. "You made that yourself?"
"With time and patience," Kakashi said simply.
Sasuke watched silently, eyes narrowing as he memorized every glowing mark. He felt it again, how far ahead Kakashi was. And yet… he was no longer jealous.
He was inspired.
"Kakashi-sensei…" Sasuke said, stepping forward. "Teach me the foundation for this too. I want to understand it."
"You're not ready for the complex parts yet," Kakashi said, but then added with a soft smile, "But we'll get there. One seal at a time."