"Guxuan, I've passed the first test. Can we start the second one now?"
Son Goku asked impatiently.
"Are you in such a hurry? All right, let's begin the second test."
Guxuan smiled and replied casually.
He didn't mind either way, but since Son Goku had asked, they might as well begin.
"What's the second test?"
Boom!
The answer came in the form of the power that erupted from Guxuan.
Guxuan's power was now far greater than before.
"That's incredible! You're much stronger than you were when you fought Lord Beerus!"
Son Goku's gaze sharpened as he looked at Guxuan.
"Son Goku, after my battle with Beerus, my power in my normal state reached one hundred trillion."
Guxuan unleashed his full power and spoke slowly.
"By your standards, that's equivalent to one quadrillion. You can't even imagine how powerful that is right now.
"I don't expect you to beat me without transforming into a Super Saiyan.
"If you can last for an hour against one-tenth of my normal power without transforming into a Super Saiyan, you'll pass the second test."
Guxuan spoke slowly.
"Of course, you can use anything you like except transforming into a Super Saiyan. Kaioken, Spirit Bomb, whatever you can think of—feel free to try it."
Guxuan explained the second test.
"One-tenth? I should be able to last an hour."
Son Goku looked at Guxuan.
Whoosh!
Son Goku shot forward at incredible speed, charging straight at Guxuan.
He was so fast that even Guxuan's eyes narrowed in surprise when he saw him.
"I didn't expect him to have gotten so much stronger. He's really surprised me."
Guxuan said, astonished.
Bam!
Bam! Bam!
Bam! Bam! Bam!
Son Goku attacked without pause, each strike incredibly fast. His power remained just as consistent as his speed.
That alone would have been nothing special.
What really caught Guxuan's attention was that Son Goku's attacks kept getting stronger.
"As expected of the Saiyans, a warrior race. That certainly suits him."
Guxuan was very pleased with Son Goku's performance.
Even so, his strength far surpassed Son Goku's.
No matter how hard Son Goku tried, it was useless under the circumstances.
His attacks had no effect on Guxuan at all.
Even a full-power strike couldn't injure him.
But the reverse was another matter.
Even Guxuan's casual strikes were a huge challenge for Son Goku.
The slightest hit would leave him seriously injured.
Guxuan finally got to experience the thrill he'd felt when he fought Beerus.
Only this time, he was in Beerus's position, while Son Goku was the one at a disadvantage.
And so, three days passed in the blink of an eye.
Throughout those three days, Son Goku and Guxuan fought nonstop.
But the outcome was always the same: each fight ended with Son Goku badly injured by Guxuan.
This didn't happen just once a day. It happened every hour, meaning Son Goku was seriously injured at least twenty times a day.
And each time, Guxuan refused to let Son Goku eat a Senzu Bean, making him recover on his own.
Those three days were a living nightmare for Son Goku.
Even a battle-loving Saiyan like him found his daily fights with Guxuan almost unbearable.
Every time he had to recover from his injuries, it was sheer torture, and he could barely stand it.
Still, Son Goku wasn't making no progress.
At the very least, he could last longer.
At first, he could only hold out for a few seconds. Now, he could last several minutes. That was progress.
He was still a long way from Guxuan's one-hour requirement, but it had only been three days.
While Son Goku endured hellish training in the valley, Vegeta was having no easier a time over in the God of Destruction Realm.
Whis's training methods were a little different, but they were still a challenge for Vegeta.
Time passed without anyone noticing. In the blink of an eye, a year had gone by.
Over that year, both Son Goku and Vegeta had made tremendous progress.
And during the year he spent helping train Son Goku, Guxuan had also successfully learned King Kai's signature technique, the Kaioken.
What's more, he'd improved it. His Kaioken didn't have the same drawbacks as Son Goku's.
Unlike Son Goku, Guxuan's Kaioken had no side effects and put no strain on his body.
That meant Guxuan could use the Kaioken to increase his power without worrying that his body wouldn't be able to handle it.
As for his strength, over the course of that year, he'd fully mastered it.
Now, Guxuan was in his strongest state.
"Son Goku, after a year of training, you're now strong enough to transform into a Super Saiyan 4.
"But while transforming into a Super Saiyan 4 won't be a problem for you, it's still a mortal form.
"You'll also need God Ki. Only then will you be able to sense the presence of gods and survive in space."
Guxuan looked at Son Goku.
"Now transform into a Super Saiyan for me!"
Guxuan glanced at the tail that had grown back behind Son Goku, a gleam flashing in his eyes as he spoke.
"No problem!"
Son Goku nodded.
After a year of training, his battle power in his normal state had now reached eighty billion.
And after transforming into a Super Saiyan, he would become even stronger.
Boom!
An immensely powerful force erupted from Son Goku.
His battle power of eighty billion began to soar wildly.
Ten times, twenty times, thirty times, fifty times, one hundred times, three hundred times—
Son Goku's power surged without end, as if it had no limit.
"Not bad."
Guxuan nodded, very pleased with Son Goku's improvement.
Boom!
Fur began to grow all over Son Goku's body, and his hair changed from gold to black. In that instant, he transformed into a Super Saiyan 4.
An immensely powerful force burst from Son Goku, brimming with unimaginable might.
"Super Saiyan 4!"