Tobirama Senju was born twenty-eight years before Konoha was founded. He was thirty-four this year.
After marrying Senju Touka, Tobirama had not found the peace he had imagined. The sight of Touka's hands being severed continued to haunt him like a nightmare, impossible to dispel.
He had been searching for a way to truly calm himself.
Was it his elder brother's suggestion that he study Medical Ninjutsu with Toji?
No.
Though the Reverse Cursed Technique he and Toji had developed together was powerful, it was not omnipotent.
Against an opponent who was too strong, one would still die before treatment could be received.
When people were killed, they died.
That was an eternal truth of the Shinobi World, unchanged for a thousand years.
But ninja were beings who constantly defied common sense. Since they could command wind, fire, water, and earth, and stitch skin and set bones...
Could they go one step further—
Break through the boundary between life and death and bring the dead back to life?
That way, even if someone important to himself or the village died unexpectedly one day, there would be one final safeguard.
Such a twisted notion, one that blurred the boundary between life and death, quietly took root in Tobirama's heart. From a tiny seed, it swiftly rooted and sprouted, growing into a towering tree that blotted out the sky.
Tobirama began putting it into action.
He knew very well.
His elder brother would never allow him to do this, so he had to keep it from Hashirama.
He secretly established a Laboratory on the outskirts of the village. Whenever he had leave after completing a mission, he would use "facial recognition" to take prisoners out of Konoha Prison.
Hashirama Senju was kindhearted, but Tobirama Senju had never been soft-hearted.
He directly used those he had taken as experimental materials and began developing the forbidden technique in his heart, a technique capable of overturning life and death and twisting common sense.
He named it—
Impure World Reincarnation.
Absorbed in his research, Tobirama did not go to the Hokage Building for a meeting. Instead, he came to his secret Laboratory.
A burly man was tied to the operating table. The instant he saw Tobirama Senju, terror flooded his face, and his body shook violently beyond his control. Muffled roars of "Mm! Mm!" continuously came from his sealed mouth.
"Too noisy."
With a flick of his hand and a slash of his blade, Tobirama cleanly dealt with the man.
After a long and tedious preparation process, he placed his hand on the man's corpse and formed hand seals in a low voice. "Summoning Technique!"
A summoning pattern instantly spread across the corpse, but...
Nothing happened.
Tobirama withdrew his hand expressionlessly, not discouraged in the slightest.
If the boundary between life and death could be crossed after only a few attempts, that would be truly absurd.
Tobirama was about to dispose of the corpse,
When he suddenly seemed to sense something amiss, he abruptly raised his head toward a corner of the Laboratory and shouted coldly, "Who's there?!"
From the shadows,
Hashirama Senju, clad in a Hokage cloak, slowly emerged.
Hashirama's face was frighteningly grim. "Tobirama, you've gotten awfully bold."
"Big... Brother..." Tobirama froze as if struck by lightning and muttered instinctively, "Let me explain. It's not what you think."
Tobirama had considered the possibility of his experiments being exposed, but he had never imagined that day would come so quickly.
Why had this happened?
A hint of annoyance flashed through Tobirama's heart. His frequent absences from meetings lately had most likely aroused his elder brother's suspicions.
But he had no other choice.
He was already thirty-four this year.
How many thirty years did a person have? For a ninja, reaching this age already counted as a long life.
His prime had already passed. His physical functions and energy were inevitably declining. Not everyone was like his elder brother, Hashirama Senju, who only grew stronger after turning thirty.
Tobirama had to seize every day. Only then would he have a chance to develop Impure World Reincarnation within his lifetime.
"Thinking back..."
"If I were ten years younger, I'd have plenty of time, and my elder brother wouldn't have discovered me."
That was what Tobirama thought to himself.
But regardless of what he thought, Hashirama's reprimand was already raining down on him.
"You don't need to explain. My eyes may not be Sharingan, but they can still see."
Hashirama said disappointedly, "Tobirama, I told you a year ago to learn proper medical arts from Toji and stop researching those strange forbidden techniques. We Senju ninja should be open and aboveboard."
"You clearly treated my words as nothing more than wind in your ears."
"Developing forbidden techniques would have been one thing, but you actually had the nerve to go even further and conduct human experiments!"
Hashirama's gaze fell upon the experimental subject Tobirama had just killed, and his expression darkened even further. If Tobirama had merely been developing forbidden techniques, he could have turned a blind eye. But once Tobirama crossed the line into human experimentation, he could not tolerate it.
Once a person crossed that line, they would continue to fall deeper and deeper.
Today, he dared to target criminals. Tomorrow, perhaps he would dare to target ordinary villagers.
If it truly came to that...
Even Hashirama did not dare imagine what he might do to his own younger brother.
"I really need to discipline you properly in Father's place."
Toji and Chiri stood side by side not far outside the underground Laboratory.
Chiri spoke. "Lord Hokage is very angry. Elder Tobirama will probably have a hard time this time..."
"As he should." Toji's expression remained calm. "No matter the reason, human experimentation is an evil taboo. If it were me, I would never allow such a thing to happen in Konoha."
He said it without changing expression.
If possible, no one wanted to conduct forbidden experiments under the nose of the God of Shinobi. But it had to be admitted that in these troubled times, only Konoha possessed the stable conditions needed to support large-scale research.
That was true now, and it would remain true in the future.
Soon.
Tobirama, bruised and battered, was "dragged" out of the Laboratory by Hashirama like a child who had done wrong and taken back to the Senju Compound.
Immediately afterward, another Hashirama emerged from the underground Laboratory and walked toward the two of them.
"That one just now was Lord Hokage's Wood Clone Technique," Chiri explained from the side.
Toji nodded, while also noticing the huge scroll hanging from Hashirama's back.
Was that the prototype of the future Book of Seals?
Toji guessed inwardly.
"Toji."
When Hashirama saw the two of them, his expression softened slightly. He was not so unreasonable as to take his anger out on others.
Toji answered, "Lord Hokage."
Exposing Tobirama's human experiments had not been a spur-of-the-moment decision, but a choice Toji had made after careful consideration.
First, it would give Tobirama some trouble. Then, when Tobirama was down, Toji could offer help in his hour of need and earn his goodwill. Second, Toji wanted to see how Hashirama would deal with his own younger brother, so he could use it as a reference.
Toji had watched Ultraman in his previous life, and there had been a plot like this—
[Ultraman Father's close friend Belial touched the Plasma Spark and was expelled from the Land of Light; meanwhile, Zero, the eldest young master of the Land of Light, committed the same mistake and was merely confined to train.]
And Tobirama was likewise Konoha's "eldest young master."
Lastly, Toji wanted to take this opportunity to inspect Tobirama's Laboratory and see whether there were any surprises.
Hashirama sighed. "Your guess was right. Tobirama really was secretly conducting human experiments to develop forbidden techniques. I gave him a thorough beating and punished him with three months of confinement for reflection."
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