After Piccolo and the other six Z Warriors boarded a spaceship and headed for Namek, Goku flew alone toward Heaven.
He had been considering an idea for a long time, one that could potentially elevate his strength to a whole new level. Today, he intended to test it.
In Heaven, Popo was tending to the surroundings as usual. When he saw Goku arrive, he said, "Goku, it's been a while."
"Yeah! Long time no see, Popo. I want to enter the Spirit Time Chamber," Goku stated plainly.
At that moment, Kami walked out of his room and asked, "Goku, your strength is already unmatched on Earth. Why do you still push yourself to continuously improve?"
Goku smiled. "Do you really think I'm invincible in the universe already?"
Kami understood what Goku was pursuing.
He nodded. "I see. Popo, go help Goku open the Spirit Time Chamber."
"Yes, Kami," Popo replied, leading Goku to the chamber.
Once inside the Spirit Time Chamber, Goku looked around at the empty white environment and muttered to himself, "Then let's see if I can reach Super Saiyan 4."
He shook his head slightly. He had only recently mastered full power Super Saiyan and had yet to reach Super Saiyan 2.
Now he was attempting to skip straight to Super Saiyan 4.
Walking across the white ground, he felt nothing from the ten times gravity of the chamber—he had already adapted to four hundred times gravity.
Raising his hand, Goku formed a ball of energy and threw it into the air.
"Explode! Artificial moon!"
The energy ball exploded, forming an artificial moon that hung in the chamber.
Goku was confident he wouldn't lose his mind during the transformation—he had made a wish to Shenlong to maintain his sanity even as a giant ape, an essential step toward achieving Super Saiyan 4.
The conditions for a Saiyan to transform into a giant ape were the reception of Bruzwaves. Once the power exceeded 1,700W, the Saiyan would transform.
The moon was not the only source—it just happened to emit Bruzwaves. Many stars could do so, and Saiyans had historically used their giant ape transformation to conquer planets.
Goku's body erupted in power as he fully transformed into a giant ape. His combat power skyrocketed from 2.2 million to 220 million.
Now, he focused on channeling the Super Saiyan energy within his giant ape form. Mobilizing it proved challenging.
"This is harder than I thought. But I can't fail," Goku muttered, determination blazing in his eyes.
Time passed slowly. Three hours later, the artificial moon disappeared, but Goku had yet to fully harness the Super Saiyan energy in his giant ape form.
The energy surged violently within him. Golden aura radiated from his massive body, becoming brighter and more intense. Every cell of his body pulsed with incredible power.
Finally, all the Super Saiyan energy within him erupted. Goku completely transformed into a golden giant ape.
The aura around him surged, increasing his combat power fiftyfold compared to the normal giant ape form—five hundred times his base power.
"This is… incredible," Goku muttered, awed by the sheer strength coursing through his body.
Checking his power with the detection ability granted by his wish to Shenlong, Goku realized it had maxed out. His combat power now exceeded the measurable limits, clearly beyond 10 billion.
"Now, I need to compress all this energy into my own body," Goku said.
The golden giant ape began to radiate an explosive energy, shaking the entire Spirit Time Chamber.
The compression process was excruciating, but Goku steadily forced the power into himself.
As the energy condensed, his body began to shrink from the giant ape form, maintaining the golden aura and the full power he had just harnessed.
At last, Goku emerged from the process, standing as a human-sized warrior—but with power far surpassing even his previous limits.
He had successfully condensed the golden giant ape energy within himself, taking the first real step toward Super Saiyan 4.