Starting as a Ninja in the Naruto World

"It's really him…"

Black Zetsu was conflicted.

It was a strange mix of joy and unease.

Emiya Shigen's sudden appearance in this era was completely unexpected.

Even though Emiya betrayed Black Zetsu during the ancient era, Zetsu couldn't help but feel nostalgic about their time working together.

This was a peculiar feeling…

It felt like encountering someone breathtaking during the lowest point of your life.

Every time Black Zetsu thought about Emiya Shigen, memories of their first encounter would flood back.

That day…

Emiya Shigen was trying to assassinate Indra.

At that time…

Indra had only awakened the Three Tomoe Sharingan.

And back then…

Black Zetsu thought Shigen was just a small fry looking to die.

But what followed nearly scared Black Zetsu to death.

Because Shigen wasn't an ordinary man.

He had gained the power of Wood Release and natural energy from remnants of the God Tree.

He was a master swordsman and taijutsu expert, accompanied by a tiny slug on his shoulder.

In their battle, Shigen utterly dominated Indra, leaving him with no chance to fight back.

At first, Black Zetsu was lurking in the shadows to aid Indra if needed.

But Shigen noticed him.

Realizing that Indra had backup, Shigen abandoned the assassination attempt and left.

But Zetsu couldn't escape.

That was the day Black Zetsu was forced to introduce himself to Emiya Shigen.

And that's when he learned of Shigen's true intentions.

Emiya Shigen's goal was to destroy the ninja system created by Hagoromo.

After all, Hagoromo's teachings had spread too far.

Many of his disciples left to share the knowledge of chakra in their homelands.

Some disciples used chakra for good, helping their people.

But others became greedy, using chakra to seize power and wealth.

Emiya Shigen had been a victim of that greed.

One day, a former ninja monk, now a rogue shinobi, massacred an entire village just to steal a few bottles of sake.

Emiya survived only because he had been traveling outside the village.

Driven by vengeance, Emiya Shigen prayed to the remnants of the God Tree, hoping for power to bring justice.

In return, the God Tree's remnants granted him Wood Release.

But no matter how powerful his newfound abilities were,

To challenge Hagoromo the Sage of Six Paths was nothing short of madness.

At that time, Black Zetsu didn't think Emiya would amount to much.

He barely paid attention to the man afterward.

All Zetsu knew was that Emiya Shigen wandered the ninja world, saving lives and spreading his philosophy of medical ninjutsu.

Meanwhile, Black Zetsu was on top of the world.

For the first time, his plan was succeeding.

He had successfully manipulated Indra into fighting Ashura, hoping that Indra would steal Ashura's power and awaken the Rinnegan.

But then…

Indra lost.

Humiliated by defeat, Indra vanished into the shadows.

And Black Zetsu's first grand plan crumbled.

Defeated and dejected, Zetsu went into hiding.

While Zetsu was licking his wounds,

Emiya Shigen was still out there, saving people.

Shigen preached that chakra should be used to relieve people's pain,

Not as a weapon to cause suffering.

During those dark years, Emiya Shigen's influence grew.

He became more respected than even Hagoromo himself.

Why?

Because Hagoromo had destroyed humanity's faith by cutting down the God Tree.

But Shigen never abandoned the people's beliefs.

He still respected the divinity of the natural world and used his power to heal.

People revered him.

Even Hagoromo and Ashura held deep admiration for Shigen.

He wasn't just a healer.

He was the founder of medical ninjutsu.

A man who endured humanity's unbearable suffering and still chose to bring relief.

Even Black Zetsu admired him.

It was rare for a villain to like a hero.

But Zetsu found himself fascinated by Shigen's unwavering kindness.

And as a master manipulator, Zetsu saw Shigen as the perfect pawn.

In those dark days of defeat,

Zetsu found solace in Shigen's company.

Together, they mocked Hagoromo's hypocrisy and criticized the rogue disciples of the ninja religion.

Over time, Shigen learned many secrets from Zetsu.

Including the origin of chakra and the truth about Hagoromo.

But there was one secret that changed everything.

Shigen discovered Hagoromo's corpse.

Driven by his thirst for knowledge,

Shigen wanted to dissect the Sage of Six Paths.

He wasn't seeking power.

He wanted to study the human body to improve his medical techniques.

Shigen was the first ninja to conduct human autopsies.

He even told Zetsu that, after his death,

He wanted his own body preserved as a medical specimen.

Eventually, Shigen stole Hagoromo's corpse and brought it to Ryuchi Cave.

There, he studied the Sage's remains and gained a portion of his power.

By the time Shigen reappeared,

He had already transplanted the Rinnegan and was commanding giant slugs in battle.

Zetsu had never imagined that a human could achieve such results through medical science.

For a moment…

Zetsu believed his plan would succeed.

Shigen destroyed the Ninja Order.

He slaughtered countless disciples and reduced their village to rubble.

He was one step away from erasing Hagoromo's legacy.

It was the closest Zetsu ever came to victory.

But then…

Shigen lost.

Because he met Ashura.

The two had crossed paths long ago, when Ashura was digging wells to help a struggling village.

Shigen saw Ashura as a kind-hearted man.

And when Ashura pleaded for peace,

Shigen chose to believe him.

In the end,

Shigen handed his dream to Ashura.

To atone for his sins,

He used the Rinnegan's power to resurrect those he had killed.

Afterward, he returned to Ryuchi Cave and prepared his body for preservation.

When he reappeared,

His body was sealed in a crystal coffin, entrusted to Ashura.

"Such a fool…"

Zetsu often thought to himself.

If only Shigen hadn't trusted Ashura,

Everything would be different.

"Ha… ha ha ha…"

Zetsu let out a mocking laugh.

"I wonder…

Will Shigen regret his past choices?

Now that he sees what the ninja world has become?"