"Old man Tobirama, I didn't expect you to be that kind of person behind my back!"
Renya kicked the study door open and stormed in furiously.
Senju Tobirama lowered the book in his hands and lifted his gaze, meeting Renya's eyes that were filled with anger.
His expression remained calm and composed as always—but upon closer inspection, there was a hint of unease flickering in those eyes.
He opened his mouth slightly but didn't know what to say…
At first, when his elder brother forced him to adopt Renya, Tobirama hadn't felt much goodwill toward this suddenly-appearing Uchiha brat.
The Senju and Uchiha had always been mortal enemies; the hatred between the two clans could not be easily erased.
If his elder brother hadn't forced him, he would never have taken Renya in—no matter what.
But what was done was done; he could only accept it.
Since he had already adopted the kid, he couldn't waste such a perfect opportunity for research.
And so, Tobirama began studying the structure of the Uchiha body, hoping to discover the clan's weaknesses through Renya.
He believed that, given the Uchiha temperament, they would one day pose a danger to the village—so he needed to prepare in advance.
However, as time passed and he spent more days with Renya, he realized the boy was different from the others of his clan.
Gradually, he came to acknowledge him.
From that point onward, Tobirama began to see Renya as his successor.
Ever since he injected his own blood into Renya's body, Tobirama had constantly worried that Renya would suffer backlash.
He made it a routine to monitor Renya's condition closely, checking every parameter, fearing something might go wrong.
And thus, the experiments continued for a full twenty years.
Fortunately, his fears had been unnecessary...
Renya's body not only showed no negative effects—it actually grew stronger and stronger as he aged.
Just when Tobirama thought everything was fine, a second personality suddenly appeared within Renya's body!
That guy would occasionally take over Renya's body and come into Tobirama's office just to annoy him.
The existence of this second personality was a constant threat—Tobirama could never allow it to remain.
If it could seize control once, it could do it again. And if left unchecked, it might permanently take over Renya's body.
To eliminate it completely, Tobirama spent five whole years.
But what he hadn't expected was that once the second personality was destroyed, its memories would resurface in Renya's mind—revealing the secret of the experiments...
The secret Tobirama had hidden for twenty years was finally exposed.
But he did not regret it—the second personality had to be destroyed!
Even if it meant Renya learning the truth, Tobirama would still do the same.
"Old man, aren't you going to explain what you've done?" Renya glared at him with a dark expression.
He had been standing here for a while, and the old man hadn't said a word.
That silence made him furious.
Sure, he knew the experiments hadn't actually harmed him—but it was the feeling of being deceived that pissed him off.
It was like when parents secretly do something outrageous "for their child's good"—and when the child finds out, their blood pressure spikes instantly.
That's exactly how Renya felt right now.
And the fact that the old man still refused to speak only made it worse.
Was he really not going to give him an explanation?
Renya remembered everything from the second personality's memories—how the old man had fought that other self for five years to protect him.
But that still wasn't a reason to secretly use him as a lab experiment!
If Tobirama had just been honest from the start, Renya wouldn't have been nearly as angry.
Sure, his physique had improved while doing nothing—but no one would feel good about being experimented on behind their back.
...
After a long silence, Tobirama finally spoke.
"Sorry, kid."
"You..." Renya's mind froze for a moment.
He hadn't expected the old man to suddenly apologize, and all the words he'd prepared to yell got stuck in his throat.
He apologized? Just like that? Then… what was he supposed to do now?
Renya felt a bit lost—but quickly snapped out of it.
No! He'd been used as a lab rat for twenty years—there's no way a simple apology would make that right!
"Old man, don't tell me you think a single 'sorry' can settle this?" Renya's eyes narrowed at Tobirama's face.
For a second there, he'd almost fallen for it.
"I know you're angry right now," Tobirama said evenly. "And yes, I did experiment on you. But I want to say—I'll take full responsibility for it."
He looked straight into Renya's eyes, his tone solemn.
"I apologize to you, Renya. I'm sorry."
No excuses, no fancy words, no attempt to shift the blame—and not even a plea for forgiveness.
Just a statement of fact and a straightforward apology.
Some things, once done, don't need excuses.
From the moment he started experimenting on Renya, Tobirama knew this day would come eventually.
There are no walls that keep secrets forever.
He didn't expect Renya to forgive him—but he didn't want the boy to do anything rash because of it.
Renya looked at the man who had lived with him for twenty years.
Hearing that apology, all the anger and resentment in his chest felt like a balloon that had suddenly deflated.
He wanted to confront the old man because it just didn't sit right with him—
Being turned into a lab rat without knowing for twenty years? Anyone would be angry.
But inheriting the second personality's memories had helped keep his emotions in check.
This old man hadn't treated him badly—and the experiment hadn't actually caused harm.
Renya wasn't going to do anything to Tobirama, nor would he ever consider betraying the village or destroying the Shinobi World out of rage.
Twenty years of shared bond wasn't something fake.
He couldn't possibly kill Tobirama over this, then run off to join Uchiha Madara and live in a cave like some hermit on a mountaintop, right?
Only a true-born Uchiha would do something that extreme—he, a half-blood, could never go that far.
"Old man, you really let me down," Renya said with irritation. "Don't expect me to cook for you for a while. I'm leaving the village to clear my head."
Since things had come to this, he might as well take the opportunity to leave and go find Uchiha Madara—maybe even brag about his Mangekyō Sharingan a little.
He felt so strong now, he could probably pin the old man Madara to the ground and beat him up.
Though, to be safe, maybe he should wait another ten years or so first.
...
Tobirama had no reason to object. He agreed without hesitation, and the tension in his heart finally eased.
Thank goodness Renya wasn't cutting him off completely.
He'd just have to go without good food for a while.
Sure, it'd be uncomfortable—but that was a small price to pay.
After all, he had been in the wrong.
"Old man, that's it then," Renya said as he turned to leave the study. "This matter ends here."
Tobirama watched his back as he left, and couldn't help but smile.
"Things aren't as bad as I thought..."