The Rampaging Incursio

The recent treatment had consumed a vast amount of Tsunade's chakra and mental energy, leaving her visibly drained.

Yusuke stepped directly to her side, allowing her to lean against him.

"I've only managed to fuse a tiny wisp of Sage chakra; I'm still a long way from fully entering Sage Mode."

Yusuke exhaled a long, heavy breath, his voice laced with exhaustion yet brimming with excitement.

Sage Slug: Although I haven't eaten dinner, why do I feel so full?

The Sage Slug's voice carried a note of approval: "A very good start."

"Your aptitude and willpower have both exceeded my expectations."

"Rest for a moment and commit this feeling to memory. Sage arts training cannot be rushed."

Yusuke nodded, not forcing himself further.

However, just as that wisp of Sage chakra was about to be exhausted, a sudden anomaly occurred within Yusuke's body.

The faint Sage chakra inside him was instantly swallowed by a darkness that appeared out of thin air.

A tyrannical consciousness, lurking in the deepest recesses of his body, had suddenly awakened.

It had caught the scent of something incredibly delicious.

After annihilating the Sage chakra Yusuke had condensed, it seized control of his body in reverse.

With an efficiency a hundred times more violent than before, it began frantically drawing in the natural energy of Shikkotsu Forest.

This was exactly what it wanted.

"Yusuke, have you lost your mind?! Stop it at once!"

Tsunade's face turned pale with horror.

This whale-like absorption speed far exceeded any safety limit; the natural energy would instantly shatter the balance between his physical and mental energy.

There was only one outcome awaiting Yusuke—his body would be completely disintegrated by the natural energy, leaving not even a corpse behind!

Ignoring her own depletion, Tsunade's palms glowed once more with the green light of the Mystical Palm Technique, attempting to intervene forcibly and stabilize the raging energy flow within Yusuke.

But at this moment, most of the control over Yusuke's body had been seized by that dark entity, and a look of extreme pain and struggle flashed across his face.

His remaining consciousness allowed him to use his last ounce of strength to pour chakra into his arm, shoving Tsunade away from his embrace.

"Stay back!"

A gentle force sent Tsunade stumbling backward, far from the center of the energy vortex.

Immediately after, the suction force on Yusuke's body surged again.

Centered on him, an invisible black hole seemed to form, and the surrounding natural energy poured madly into his body.

His skin began to bulge irregularly, as if something were rampaging inside, and his meridians emitted a mournful whine under the unbearable strain.

The Sage Slug's gentle voice took on a grave tone for the first time: "There is a 'foreign object' inside him, using the natural energy to awaken."

"If this continues, he will only die; there is no other outcome."

Before the words had even faded, dozens of small slugs split off from the Sage Slug's body, moving like a blue tide as they crawled rapidly toward Yusuke.

One by one, the small slugs attached themselves to the key acupoints on Yusuke's body, their bodies glowing with a soft, healing light.

They attempted to use their own life energy to neutralize and channel the runaway natural energy, stabilizing Yusuke's crumbling physical form.

At this moment, Yusuke's perception was forced entirely inward, and his "vision" plunged into chaos.

The meridian system that had originally balanced the three types of energy was now stained an ominous, dark color.

That dark entity was no longer a vague shadow.

After absorbing a massive amount of natural energy and Yusuke's own chakra, it had expanded rapidly.

It transformed into a massive, sky-obscuring storm cloud that filled his mental space.

The clouds churned, radiating a cold and violent aura.

Then, the clouds began to contract and condense inward.

A silhouette gradually became clear: its skin was dark red like blood, covered in sharp bone spurs.

It possessed the head shape of a dragon, but far more twisted and hideous, with four blood-red Cross-Star Eyes flickering with pure, destructive desire.

Its giant maw split open, revealing layers of dagger-like fangs.

"ROAR!"

A tyrannical sound erupted, leaving Yusuke's consciousness reeling.

"This is... Tyrant!" Yusuke recognized it instantly.

This was the source used to create Incursio, that legendary dragon-type Danger Beast, rumored to be a monster possessing ultimate adaptability and survival capabilities.

Even after being forged into a Teigu, it had retained its vitality, which was the reason why the Teigu Incursio could evolve infinitely.

Yusuke's long-standing fear had become reality.

The power of the Teigu Incursio needs no explanation, but the risk lies in the fact that with each use, the user is gradually consumed by the materials from which it was forged.

Eventually, one would undergo a complete dragon transformation, losing their sense of self.

He used it cautiously every time, fearing that he might overstimulate the slumbering beast.

However, the vast and pure natural energy of Shikkotsu Forest was the perfect nourishment for Tyrant.

No longer content to lie dormant, it awakened and grew rapidly under the stimulation of the natural energy.

Its next step was to erode Yusuke's mental core, making Yusuke a sacrifice for its own rebirth.

"Roar!"

Tyrant's consciousness roared once more, filled with wildness and brutality, directly assaulting Yusuke's mind.

Four Cross-Star Eyes locked onto Yusuke's core consciousness, brimming with a hunger to devour and possess.

Externally, Yusuke's physical condition took a sharp turn for the worse.

The small Sage Slug clones attached to his body fluctuated violently; the stable energy they were channeling was being rapidly neutralized by a darker, greedier force.

The Sage Mode markings on Yusuke's face flickered unsteadily, his silver hair showed signs of shifting toward a dark red, and faint, dragon-scale-like protrusions even began to emerge beneath his skin.

"A powerful negative will is seizing control."

"Little Tsunade, stay back. I am going to increase the energy output and attempt to suppress this will."

Sage Slug's voice carried an unprecedented gravity; it could sense that the monster within Yusuke was, at its peak, no weaker than itself.

More small slugs split from the main body of the Sage, surging toward Yusuke like a blue tide.

This time, it was not for restoration, but to weave a cage out of natural energy to seal the dark will within Yusuke.

Internally.

"I won't let you succeed." Yusuke growled, enduring the excruciating pain of his soul being torn apart as he quickly thought of a solution.

"The core of Shikkotsu Forest's Sage Art is balance, it is life force..."

"And Tyrant represents destruction, it is consumption."

"Where there is Yin, there is Yang; where there is growth, there is decay; where there is life, there is destruction. The two are fundamentally opposed!"

An extremely risky plan took shape in his mind.

What he had to do next was not to expel or suppress, but to... tame.

He would use the balancing nature of Shikkotsu Forest's Sage Art to place a shackle upon this tyrannical beast.

Abandoning the futile attempt to fight for control over the energy, he sank his entire focus into guiding the natural energy.

Yusuke actively guided the remaining physical and mental energy within his body, fusing them in a perfect ratio.

This energy was rapidly woven into a great net, actively entangling Tyrant's dark and brutal consciousness.

"Roar!"

Tyrant's consciousness let out a painful shriek.

Natural energy filled with life force was its favorite, but only if it did not contain the will of another.

By fusing his own chakra with the natural energy, Yusuke made it impossible for the beast to devour it.

But it was simply too strong; its four blood-red eyes flared with light as it struggled frantically, attempting to tear the energy bindings apart.