A Chakra-concealing barrier covered the outer perimeter of the wall—its entire purpose was to disrupt sensory techniques. That was why no one had detected the facility earlier.
The two quietly selected a section of the wall and used a specialized Ninjutsu designed not to disturb the barrier's structure.
Senju Hashirama extended a finger. A searing jet of flame burst forth like a focused flamethrower, carving a perfect circle into the stone.
The marked section fell inward with a dull thud.
After slipping inside, the two restored the surface behind them using Earth Release in an unconventional way—a simple technique in theory, but one that required precise Chakra nature transformation.
A brief glance was exchanged.
Then they began moving deeper into the hidden passage.
The dim ceiling lights stretched ahead at regular intervals—fifteen meters apart—uncannily reminiscent of the underground experimental bases once built by Orochimaru. The corridor extended far into the darkness, with branching passages splitting left and right.
With a nod, they separated—each heading down a different path at high speed.
Senju Hashirama followed the corridor for about a minute before arriving at a fork. He paused, scratching his head.
"…Right. I'll just do it like this."
He clapped his hands lightly and produced a dice from his pocket.
"Small goes left. Large goes right."
The dice spun upward, then fell into his palm. A small number.
Left it was.
Hashirama continued through the winding passage. After a few more turns, several doors came into view—but what immediately caught his attention was the large circular training ground at the far end.
A training ground, hidden inside a mountain?
That alone was suspicious.
But Hashirama pushed that thought aside for now and approached the nearest doorway.
Above it hung a small sign:
Archive Room
If there was anywhere with actual information, it would be here.
After checking carefully to confirm no one was inside, Hashirama pushed the door open.
A faint click… click… accompanied the movement of the hinges. The room beyond was compact—rows of shelves lined the right wall, all of them empty.
Hashirama frowned. Had everything been cleared out already?
Only a table in the center held a few scattered files—damaged ones, torn diagonally across the page as if removed in a hurry.
The overhead spotlight cast a narrow pool of light. There were no windows, only ventilation ducts overhead. The walls were embedded with dull yellow crystalline materials that functioned like low-grade illumination stones, providing a faint glow.
He picked up what remained of the documents and flipped through them carefully.
Their contents were… strange.
"Subject 23 lost control again. Cause unknown…"
"Subject 25 remains intact, but shows signs of mental deterioration. Recommend…"
"Subject 31's tissue is collapsing… When will this experiment succeed… Funding insufficient. The Master is displeased…"
Fragmented notes. None complete.
A diary-like record—but clearly not one valued enough to be preserved properly.
Hashirama exhaled quietly.
Nothing useful yet.
But the tone of the entries made one thing clear—
This place was conducting dangerous human experimentation.
Exactly the kind of thing that had to be stopped.
From the fragmented files alone, it was clear the enemy had been conducting some kind of research—and whatever it was, the sense of unease in Senju Hashirama's chest only grew.
He stepped out of the archive room after quietly photographing the remaining pages, then headed to the next door roughly ten meters away.
The label read: "Specimen Room."
Hashirama's brows knit tightly.
Still, he entered.
After a careful sweep, he confirmed there were no enemy personnel nearby. He avoided using detection Ninjutsu—any Chakra flare risked drawing attention. In a place like this, stealth mattered more than speed.
He pushed the door open.
The interior was brightly lit.
And the moment his eyes adjusted, a cold fury surged through him.
Inside were human severed limbs, floating in jars of preservative fluid. Disassembled arms, legs, and torsos—some intact, some crudely stitched, some clearly taken apart for study.
Wires were scattered along the floor. And among the jars were organs that were not human—Hashirama sensed faint traces of summoned-beast Chakra coming from them. Some organs were far too large to belong to ordinary creatures.
"What… happened here?"
The grotesque sight made the entire room feel warped—wrong in a way that scraped against instinct. Hashirama forced down the wave of nausea and began examining the shelves.
Aside from the dismembered limbs and preserved organs, there was nothing else.
Nothing that explained the purpose behind these experiments.
"This won't do. I need to find someone—and get answers."
Decision made, he exited the room and moved deeper into the hollowed-out mountain. The base was extensive—large enough to qualify as a medium-sized hidden facility, the kind even Orochimaru would be reluctant to abandon.
After traversing several kilometers of branching passages, Hashirama finally spotted someone up ahead.
He exhaled in relief—
—but before he could act, a violent explosion thundered in the distance.
Smoke rippled through the corridor.
A single thought shot across his mind:
Jiraiya!
Was he discovered?
Hashirama muttered a frustrated, "That useless teammate…" and immediately sprinted toward the blast.
In truth, Jiraiya had been found out.
The base was riddled with hidden surveillance cameras. Even though Jiraiya's stealth was exceptional—and he hadn't tripped a single trap—one misstep placed him directly within the view of a monitoring screen.
Worse still, he had wandered into the facility's core area, where security was far tighter than the peripheral storage zone Hashirama explored.
And then—
BOOM!!!
Another massive explosion shook the corridor as a three-meter-tall monstrosity was blasted backward, slamming into the wall hard enough to crack stone.
Hashirama arrived just as the creature staggered up again.
He saw Jiraiya.
Jiraiya saw him.
"Hashirama! Perfect timing!"
Hashirama rushed over. "What happened? How did you get discovered?"
"No time—just help me already!" Jiraiya snapped, exasperated.
He had stumbled upon someone conducting a biochemical experiment, interfered, and sabotaged it… which had triggered the alarm. Now, he was being relentlessly chased by the mutated brute towering before them.
The creature's muscles bulged unnaturally. Its skin stretched tight, ready to burst. Madness burned in its eyes.
A man like this wasn't a shinobi anymore.
He was a bio-weapon.
A manufactured bio-human, driven beyond reason.