"So comfortable," Sasuke lazily reclined on the grass by the river. The gentle afternoon sun bathed his face, enveloping him in a warm embrace. A soft breeze caressed his cheek, stirring ripples across the river’s surface.

"Since I have nothing else to do, I might as well see how much liquid chakra I've accumulated."

Sasuke sat up. It had been two days since he had created the illusion "Tongue Ripping Hell," which had drained a significant amount of his mental energy. Over the past two days, he had refrained from training, both personally and through his clones, spending the time in restful repose.

"Not bad; I’ve accumulated quite a bit of chakra. However, what is that…" Sasuke activated his Sharingan and discovered that his chakra now equaled that of two or three Chūnin, which left him feeling content. Yet, he suddenly noticed something troubling.

"Is that impurity?"

Sasuke murmured to himself.

"It’s unacceptable. I must remove these impurities, or else, in a decade or two, the impurities in my chakra will become overwhelming."

He deactivated his Sharingan and began contemplating methods to remove the impurities.

Impurities in chakra are a common issue for every ninja. Each use of a jutsu introduces a small amount of impurities into the chakra, an unavoidable occurrence. When one is young, these impurities are less of a concern, merely diminishing the potency of the jutsu. However, as one ages, a large accumulation of impurities can severely damage the body, as the physical condition of elderly people is far inferior to that of their younger selves. Many ninjas in the role of Hokage experience a dramatic decline in their abilities in old age, often accompanied by various ailments; the Third Hokage is a classic example.

"Ah! This is truly vexing."

Sasuke raked his fingers through his beautiful hair.

"Never mind, I’ll first head to the weapon shop to find a long sword."

He stood up and hurried towards the weapon shop. Sasuke was uncomfortable using kunai in close combat and decided to switch to a long sword. However, the usual long swords were of such poor quality that they broke after only a few uses. Today, he intended to find a better blade at the weapon shop.

—— "Excuse me, do you have any high-quality long swords?"

Sasuke arrived at the Uchiha family’s weapon shop and inquired with the shopkeeper.

"Ah! It’s Young Master Sasuke. What kind of long sword are you looking for?"

The shopkeeper turned with a friendly demeanor. In the Uchiha clan, non-ninja members are considered lower status, akin to the branch family in the Hyuga clan. Ninjas are like the main family, while non-ninjas are like the branch family, with the main family having authority over the branch family. As the son of the clan leader, Sasuke was naturally addressed as "Young Master."

"I need a long sword of exceptional quality, one meter in length, and it must be able to channel chakra."

Sasuke detailed his requirements.

"Young Master, we currently do not have a long sword that meets your specifications; it will need to be custom-made."

The shopkeeper’s face showed a tinge of bitterness upon hearing the request.

"That’s fine. How long will it take to make?"

Sasuke did not show any signs of displeasure.

"Approximately three days."

Seeing that Sasuke was not displeased, the shopkeeper breathed a sigh of relief. Sasuke seemed to have a sudden thought and asked, "When you make weapons, do you use a hammer to continuously strike the material?"

"Yes, only through repeated hammering can the impurities in the material be removed."

Though the shopkeeper was puzzled by the odd question, he answered truthfully.

"I understand."

Sasuke left the shop and hurried back home.

"Young Master, do you still want the long sword?"

The shopkeeper’s voice came from behind.

"Yes, I’ll come to collect it in three days."

Sasuke’s voice echoed from a distance.

"I wonder what Young Master is in such a hurry for? Ah, it must be for training. It seems that the elder brother (Itachi) is a genius, and even Young Master is a diligent talent."

The shopkeeper mused to himself, turning back to the shop to prepare the special sword for Sasuke.

—— "Sasuke, why are you in such a rush, all sweaty? Is something wrong?"

Mikoto Uchiha observed Sasuke rushing back home.

"Ah, Mother! I have something urgent to attend to. I’ll explain later."

Sasuke darted towards his bedroom.

"This child, what could a little boy have that’s so pressing?"

Mikoto shook her head with a smile and went to the kitchen to prepare dinner for Sasuke.

Once in his bedroom, Sasuke sat on the bed and pondered, "If chakra is like material, could it be that by continuously striking it with something, the impurities could be removed? But since chakra is within the body, we can't strike it like material. What should be done?"

He scratched his head, deeply immersed in thought.

"Water treading…"

After much contemplation, Sasuke finally devised a method: using the principle of water treading, he would channel chakra to his feet. While walking, his body would act as the hammer, and the chakra beneath his feet would be the material. Each step would "hammer" the chakra. Sasuke had learned water treading when he was just two years old.

Without hesitation, he began. "This is difficult."

During dinner, Sasuke could only walk on level ground; any uneven surfaces would cause him to lose balance.

A week later, Sasuke had mastered walking on uneven terrain using chakra.

Two weeks later, he was able to run across uneven ground effortlessly.

A month later, Sasuke could use chakra to walk smoothly on any surface, as if it were level.

"Though it’s been a month of hard work, the results are impressive."

Sasuke performed a series of advanced movements in the forest and found that, although the impurities in his chakra were not entirely removed, they had been significantly reduced. He was also pleasantly surprised to find that his chakra control had improved, as walking on uneven surfaces required constant adjustment of chakra, which served as excellent training. Additionally, he noticed a significant increase in the rate at which his chakra grew.

"It seems that using chakra while walking has many benefits. From now on, I’ll use chakra in all my movements."