The simplest method was to let natural energy slowly erode the cells, increasing their resilience bit by bit until they could fully endure the force of nature itself.

With the assistance of 120 shadow clones, Ayanami Kaito's training speed was astonishing. Within a month, the strange tentacle-like protrusions on his forehead had significantly diminished.

After two months, a faint layer of eye shadow appeared at the corners of Kaito's eyes.

By the third month, he had completely mastered perfect Sage Mode.

The rapid progress left the nearby slugs in awe.

"Kaito sama, now that you've mastered Sage Mode just like the First Hokage, would you like to learn the Forest's combat techniques?" a slug asked respectfully.

"No need to rush, slug," Kaito smiled, shaking his head. "I'll be training here for a while longer. There'll be plenty of time for those techniques after I finish this."

"Kaito sama, you've already learned Sage Mode, though. Why stay here to continue training?" the slug asked, puzzled.

"I've only just begun to grasp Sage Mode. It still takes too long to enter it. My next goal is to achieve instant activation, like the First Hokage," Kaito explained.

"I see. Do you still need our assistance, then?"

"Of course I do!" Kaito quickly replied.

Was that even a question? Training with a slug on his shoulder and training without one were two entirely different experiences.

With a slug guiding him, it took only three minutes to gather natural energy, while without one, it would take at least fifteen.

Kaito wasn't foolish — he knew exactly which option to choose.

After exchanging a few more words, Kaito re-entered training, immersing himself once again in the flow of natural energy.

Above him, threads of natural energy drifted down like mist, merging with his body, circulating through him, gradually increasing his tolerance to it.

Over and over, Kaito pushed himself tirelessly. He knew there were no shortcuts. If he wanted strength, he had to endure the solitude of relentless training.

In Kaito's mind, there were three stages to Sage Mode mastery.

The first was ordinary Sage Mode — powerful, but slow to activate, like Naruto's and Jiraiya's.

The second was complete adaptation to Sage Mode, drastically reducing the activation time. This was the legendary ability of the First Hokage, who could enter Sage Mode in an instant.

The third stage went beyond that. After the body fully adapted to natural energy, it would unconsciously absorb it passively, and as long as the natural energy gathered exceeded what was consumed during battle, one could maintain Sage Mode indefinitely.

At that level, the body's cells would undergo a fundamental transformation, possibly evolving into the so-called Immortal Body.

Of course, this was only a theory. Even with a mere one percent of the Senju bloodline, Kaito had no way of knowing if it was truly achievable.

But it was a goal worth chasing.

There was one more requirement for that third stage — one's spiritual perception needed to detect natural energy in the surrounding world.

Fortunately, Kaito had achieved this even before arriving at Shikkotsu Forest. During the week he spent with Hinata and another girl, using the tenfold training space, he'd diligently honed his perception.

Even while enjoying their company, he never stopped working.

On the sixth day, he finally sensed the presence of natural energy around him.

When that happened, his inner world underwent a dramatic change. Vibrant, colorful energy filled every corner, though it still paled in comparison to the intense natural energy saturating the Shikkotsu Forest.

But Kaito wasn't in a rush. There were still three or four years before the start of the Fourth Shinobi World War, and with the accelerated time inside his training space, he had more than enough time to push himself further.

Days turned to weeks, weeks to months.

In the blink of an eye, a full year had passed.

During that time, Kaito's mastery of Sage Mode advanced by leaps and bounds. The time it took him to enter Sage Mode with a slug's help shrank from five minutes to just one. He even began managing it unaided.

What surprised him even more was the subtle transformation of his body. His physique felt lighter, warmer, and occasionally, faint impurities were expelled from his body.

It confirmed to Kaito that his training was moving in the right direction.

Spring passed into summer, then winter came again.

By the time two years had gone by, Kaito had turned fourteen.

In the quiet, humid depths of Shikkotsu Forest, at some unknown hour, Kaito sat cross-legged on the ground, a slug still perched quietly on his shoulder.

He closed his eyes, feeling the surrounding natural energy like countless butterflies fluttering around him.

Then, with a single thought, his body drew in the natural energy like a bottomless vortex.

A powerful suction formed around him, even visible to the naked eye as the natural energy condensed and spiraled.

His body acted like a glutton devouring everything in its path.

In moments, the familiar eye shadows appeared at the corners of Kaito's eyes. As the influx of natural energy increased, those shadows deepened, becoming fully solid.

At that moment, his Sage Mode was complete.

Kaito opened his eyes and asked calmly, "How long did that take?"

"About three seconds," replied the slug on his shoulder.

"Three seconds? That's good enough," Kaito grinned, satisfied.

Finally, after reaching this milestone, Kaito's training pace could ease up a little.

He had spent two years in Shikkotsu Forest — plus twenty years within his accelerated training space. Twenty-two years of effort, to master in this time what the First Hokage once accomplished in a few months.

It made him realize once again just how far beyond ordinary bloodlines and talents the chosen protagonists truly were.

Still, he smiled wryly to himself. Who was to blame for not being born the protagonist?

"Congratulations, Kaito sama! You've finally completed the second step," the slug said with genuine admiration.

Over the years, Kaito had shared his theories and ambitions with the slug, who was utterly astounded by the scale of Kaito's ideas and courage.

So much so that the Slug Sage's consciousness descended once to observe him personally.

The Slug Sage's parting words still lingered in Kaito's mind.

---

Thank you for the Powerstones.