Raditz's expression was priceless.
He stared down at his chest in disbelief, fingers trembling as they brushed over smooth, unbroken skin. The massive hole that Piccolo's Special Beam Cannon had torn through him was gone—completely healed.
He was alive.
He slowly lifted his head to glare at me, trying to regain his usual intimidating presence.
Then he tried to summon his ki.
Nothing happened.
His eyes widened.
Panic flickered across his face.
"What… what did you do to me?" he demanded.
I crossed my arms calmly.
"I replaced your heart."
He froze.
"With a mechanical one," I continued. "It regulates your ki flow. Right now, you don't have access to it."
His breathing grew ragged. "You… you're lying."
"I'm not," I replied flatly. "Your life is literally in my hands."
He clenched his fists, struggling to stay composed.
"I'm not trying to make you my slave," I added. "But I'm also not stupid enough to let you sabotage everything I'm working for."
He stared at me in silence.
"The only reason you're still alive," I went on, "is because you're Goku's brother."
That made him flinch.
"As an incentive," I continued, "your new heart can give you power far beyond what you had before. But only if you cooperate."
His gaze sharpened. "Power…?"
I tapped a button on my tablet.
"Temporary access. Granted."
A surge rippled through his body.
Raditz gasped.
His aura flared instinctively.
"…This… this is—!"
He looked down at his hands in disbelief.
"My power… it's higher!"
"About double your old level," I said. "Just from baseline synchronization."
He swallowed.
"And that's not all."
I looked him straight in the eyes.
"There's an emergency combat mode. Battle Phase."
He hesitated. "How do I use it?"
"Just say it out loud."
Raditz inhaled sharply.
"…Activate Battle Phase."
The device responded instantly.
His aura exploded outward.
The ground cracked beneath his feet.
Raditz staggered, eyes wide.
"My… my power—!"
"Quadrupled," I explained. "You're around twelve thousand now."
For a moment, he was silent.
Then he laughed.
A rough, incredulous laugh.
"With this… I could finally smash Nappa's smug face."
I smirked faintly. "Still not strong enough to beat Vegeta. Yet."
He clicked his tongue.
I continued, "Your heart can be upgraded. Your base strength can still grow. Training still matters—just like it does for Goku."
He looked away briefly.
"…Kakarot," he muttered.
Then he turned back to me.
"Why isn't he here?"
"And… do you really have full control over that thing in my chest?"
"Yes," I answered honestly. "And Goku is training. He's preparing for Vegeta and Nappa."
Raditz froze.
"You… you know about them?"
"I know more than you think."
I stepped closer.
"There's a safeguard built in. If you try to harm me, your ki gets locked instantly."
His eyes narrowed.
"You're bluffing."
I tapped my tablet again.
His aura vanished.
Raditz collapsed to one knee, gasping.
"Try me," I said quietly.
After a moment, I restored his access.
He stood up slowly, staring at me with a mixture of fear and grudging respect.
"If you work with me," I continued, "you get stronger. You get resources. You get protection."
"And if I don't?"
"You die."
I didn't raise my voice.
I didn't need to.
"I don't want a slave," I added. "I could turn you into a mindless puppet if I wanted to. But I won't. I have standards."
He was silent for a long time.
His eyes closed.
I could see him thinking.
Weighing his pride against survival.
Against possibility.
Finally, he laughed softly.
"…You're insane," he said. "But…"
He opened his eyes.
"If what you're saying is true… if I can really surpass them…"
His voice hardened.
"I'll endure this humiliation."
I nodded.
"Good."
He turned toward the hallway.
"I'll rest," he said. "Then we'll start training."
"Smart choice."
As he walked away, I watched his back in silence.
The mechanical heart was still experimental.
It had passed every simulation.
Every stress test.
Every safety check.
But this…
Raditz was its first real trial.
A living subject.
It worked.
So far.
If I could refine this technology…
If I could make it stable…
Then maybe…
Humans wouldn't have to rely on Saiyans forever.
Maybe we wouldn't have to wait helplessly for Goku to save us every time a god or monster appeared.
Frieza.
Buu.
Zamasu.
I had seen what happened when humanity fell behind.
Once was enough.
I would not live through that again.
This wasn't about perfection.
It never was.
It was about adaptation.
About preparation.
About refusing to be powerless.
No matter what future awaited us.
And this—
This was only the beginning.