Reverse Spirit Summoning

The days spent training under Tsunade were compact and fulfilling. Uchiha Ling's daily rhythm simplified into a three-point line: the Uchiha Compound, Konoha Hospital, and Training Ground 3.

Tsunade's teaching style matched her bold and unrestrained exterior: strict, direct, and focused on achieving the ultimate results.

Her requirements for chakra control were almost harsh, far exceeding the basic tree-climbing and water-walking exercises taught at the Ninja Academy.

This high-intensity training would have been hellish torture for an ordinary genin.

However, relying on the comprehensive enhancements provided by the system, as well as the focus and comprehension of a transmigrator's soul that far exceeded his age, Uchiha Ling managed to complete every difficult task Tsunade set for him one by one.

His speed of progress often surprised even Tsunade; from the initial stage where he needed total concentration to barely succeed, he gradually moved toward ease, even finding the mental capacity to ponder the possibilities of combining chakra nature transformations.

On this day, after completing another precise Chakra Scalpel exercise—perfectly stripping the veins from a falling leaf without damaging the blade itself—Tsunade crossed her arms and nodded in satisfaction.

"Not bad, kid. Your foundation is already quite solid. Fine control of chakra is the bedrock of medical ninjutsu, and it is also the key to learning my style of taijutsu."

Tsunade walked to the center of the training ground, her expression turning serious. "Next, I am going to teach you the core summoning jutsu passed down through my Senju lineage."

Uchiha Ling's heart skipped a beat; he knew the main event had arrived. The Shikkotsu Forest contract he had long awaited was finally about to be revealed.

Tsunade bit her thumb and quickly wove a series of hand seals: Boar-Dog-Bird-Monkey-Ram. She then slammed her palm onto the ground: "Summoning Jutsu!"

Accompanied by a massive plume of white smoke, a powerful surge of chakra rippled outward.

As the smoke cleared, a giant slug, its size comparable to a small mountain, appeared on the training ground.

It was a soft, pale blue, its body supple and moist. A pair of adorable antennae sat atop its head, and the creature radiated an aura of tranquility and healing.

"Lady Tsunade."

The slug spoke in a gentle, feminine voice, and a smaller version of itself detached and landed on Tsunade's shoulder.

"Katsuyu, I called you here today to have my new disciple, Uchiha Ling, sign the summoning contract."

Tsunade patted Uchiha Ling on the shoulder and spoke to the slug.

Uchiha Ling stepped forward and bowed respectfully to the massive creature: "It is an honor to meet you, Lady Katsuyu. I am Uchiha Ling."

Katsuyu's gentle voice resonated directly in Uchiha Ling's mind: "No need for such formalities, Master Ling. Lady Tsunade has already mentioned you to me, saying you possess extraordinary medical talent. To be held in such high regard by Lady Tsunade, you must be truly remarkable."

Tsunade pulled a massive scroll from her robe and spread it out on the ground.

The scroll was already filled with names; at the very top were the names of Hashirama Senju and Tobirama Senju, followed by Tsunade's own. Beyond those, there were very few names.

"Ling, bite your thumb, press your blood here, and write your name. Then, channel your chakra, weave the seals for the Summoning Jutsu, and attempt to summon a clone of Katsuyu," Tsunade said, pointing to a blank space on the scroll.

Uchiha Ling did as he was told.

When his blood touched the scroll and he wrote "Uchiha Ling," he could clearly feel a peculiar energy fluctuation emanating from the parchment.

Immediately afterward, Uchiha Ling wove the seals for the Summoning Jutsu and channeled his own chakra.

He intentionally controlled his chakra output, as it was his first attempt. However, the moment he was about to complete the technique, an anomaly occurred!

The chakra within his body, especially the spiritual energy component, seemed to resonate with the Shikkotsu Forest—which he had just signed a contract with—in an extraordinary way.

Although his Sharingan had not been activated, the Yin release power originating from his Uchiha bloodline and the natural energy of the Shikkotsu Forest attracted each other like magnets.

Uchiha Ling felt his output chakra being sucked away by the contract scroll as if it were out of control, far exceeding what he had anticipated.

"Hmm? This amount of chakra..." Tsunade frowned, sensing something was wrong. The chakra Uchiha Ling was erupting with at this moment did not resemble that of a newly graduated genin at all; it even surpassed the level of an elite jonin, and the spiritual power contained within it was exceptionally pure and vast.

BOOM!

An even denser cloud of white smoke exploded, nearly engulfing the entire training ground.

When the smoke gradually dissipated, both Tsunade and the small Katsuyu on her shoulder wore expressions of astonishment.

"This is... Reverse Summoning?!" Tsunade exclaimed, recognizing the technique.

This was a technique that only the higher-ups of a summoning species could actively perform to forcibly summon a contractor to their sacred land.

How many years had it been since the Shikkotsu Forest had actively reverse-summoned a contractor? Even she, Tsunade, had never been summoned by the Slug Sage in this manner.

"Please do not worry, Lady Tsunade, it is the will of the main body," the giant Katsuyu clone beside Uchiha Ling reassured her. "Master Ling seems to have piqued the interest of the main body."

A light flared brilliantly, then vanished. On the training ground, the figure of Uchiha Ling had already disappeared.

Uchiha Ling felt the world spin, the scenery around him shifting rapidly as if space were folding and traversing.

In an instant, a dense, life-filled natural energy rushed toward him, making every cell in his body feel as if it were cheering and leaping for joy.

Uchiha Ling looked around and realized he was in a completely unfamiliar environment.

The sky was a hazy, pale green, emitting a soft light.

Surrounding him were enormous, strangely shaped fungal plants; some resembled towering trees, while others looked like glowing flowers.

The air was filled with moist mist, the ground beneath his feet was soft and resilient moss, and specks of phosphorescence floated in the air.

This was one of the three great summoning sacred lands—the Shikkotsu Forest.

"Welcome to the Shikkotsu Forest, Uchiha Ling," a gentle voice came from ahead.

Uchiha Ling looked up and saw a mountain formed of pure white bone in the distance.

And atop that "summit" lay a presence so vast that it defied description.

Its body seemed to merge with the entirety of Shikkotsu Forest, stretching on endlessly with no end in sight. The soft light that permeated the area appeared to emanate from its very form.

This was the Slug Sage, an ancient existence that had survived for an unknown number of years.

Compared to the Slug Sage, the slug summoned earlier at the training ground was truly like a single drop in the ocean.

Uchiha Ling could clearly sense the energy radiating from the Slug Sage; it was vast as the sea, unfathomable, and brimming with the weight of wisdom and time.

"Lord Slug Sage." Uchiha Ling suppressed the shock in his heart and bowed respectfully. When facing an existence of this caliber, it was wise to maintain the necessary reverence.

"There is no need for such formality, child." The voice of the Slug Sage resonated directly within Uchiha Ling's mind, carrying a power that soothed the soul.

"The reason I summoned you here via Reverse Summoning is that the moment you signed the contract, I sensed something unusual."