Kaio-ken

Son Goku closed his eyes and, following North Kai's guidance, began sensing the flow of ki within his body.

The way ki moved... was different from usual. It felt like all the ki in my body had been ignited... No, even stranger than that. It was like the ki had been "twisted tight"?

"First, try the onefold Kaio-ken." North Kai's voice sounded beside him, unusually stern. "Remember, take it step by step. Don't rush. This technique puts an enormous burden on the body. One mistake could injure you."

Son Goku nodded and carefully guided the ki within him along the special path North Kai had taught him.

At first, the flow of ki was somewhat clumsy, like a clogged riverbed. But as he kept trying, it gradually became smoother and began surging through his body in an entirely new way.

"Hah!"

With a low shout, a faint crimson aura suddenly burst forth around him. It was weak, but undeniably real.

The fan in North Kai's hand fell to the ground with a smack. His eyes went wide. "Y-You succeeded on your first try?!"

Son Goku felt the surging power within him and clenched his fist, a thrilled grin spreading across his face. "So this is... Kaio-ken? My strength has definitely increased a little, but it isn't enough!"

"Wait! Don't rush—"

But Son Goku had already closed his eyes and begun adjusting the flow of his ki again.

I've got the feel of onefold down. Then what about twofold? As long as I speed up the flow of ki and make that "burning" feeling stronger... like this?

His aura abruptly skyrocketed, and the pale red glow around him turned into a brilliant scarlet, like a blazing flame.

"Twofold Kaio-ken!"

Boom—!

The ground of King of Worlds Planet trembled slightly. Under ten times gravity, dust was sent flying by the force of his aura. North Kai was blown backward again and again by the gusts, his chubby cheeks jiggling in the wind.

"This... this is only the first day!" North Kai sucked in a breath, cold sweat beading on his forehead. "Goku! Stop now! Your body won't be able to take it!"

But Son Goku did not stop. He felt that he could still go further.

As he sensed the increasingly violent power within him, an unprecedented thrill rose in his heart.

I can get stronger... I can take more! This power... it's making my whole body tremble!

"Threefold Kaio-ken!"

The red aura burned even more fiercely. Son Goku's hair whipped wildly in the surging air, and flames seemed to blaze within his eyes.

"Fourfold!"

"Fivefold!"

With every increase, North Kai's heart trembled. Looking at the young man before him, he felt as though he were witnessing some kind of monster.

"Sixfold!"

"Sevenfold!"

"Eightfold!"

Above King of Worlds Planet, the scarlet aura shot straight into the sky, staining even the clouds blood-red. Son Goku's figure flickered in and out of view within the blazing energy, like a god of war.

North Kai was completely speechless. He merely stood there in a daze, the expression on his face shifting from shock to numbness, then from numbness to an almost fanatical awe.

"Ninefold!"

"Tenfold Kaio-ken—!!!"

With that final roar, the aura around Son Goku reached its peak. The crimson radiance nearly swallowed his entire body, and the terrifying presence made even King of Worlds Planet tremble faintly.

But at that moment, Son Goku's brow furrowed slightly.

My body... is starting to hurt badly. My muscles feel like countless needles are piercing them, and even my bones are groaning under the strain... Is this the limit? No, this isn't the limit. I feel like I can hold on a little longer...

He gritted his teeth, forcibly suppressing the tearing pain, and began moving his arms and legs while maintaining Tenfold Kaio-ken.

"Ha!"

"Hah!"

Every punch he threw created a piercing sonic boom. Every kick left behind a scarlet trail in the air. He darted, spun, and shifted beneath ten times gravity, moving so fast that even North Kai could barely follow him.

Watching this, North Kai muttered to himself, "A monster... this kid is practically a monster... No, even monster isn't enough to describe him..."

Ten minutes later.

"Huff... huff..."

Son Goku finally stopped moving, sweat covering his forehead. The tearing pain within him was growing increasingly intense, and he knew that if he continued, his body truly would not be able to endure it.

"Release!"

The scarlet aura vanished in an instant. Son Goku let out a long breath, his legs going weak as he nearly collapsed to his knees. He quickly braced himself with his hands on his knees and panted heavily, sweat dripping onto the cracked ground of King of Worlds Planet.

That was close... Tenfold really is the limit I can use safely. If I go any higher, my body will truly collapse. But... this kind of power is really intoxicating. Too bad Kaio-ken only makes me a real man for three seconds, so it's destined to be used only as a trump card.

North Kai hurried over, his expression incomparably complicated, filled with both worry and undisguised delight. "Goku... are you... are you all right?"

Son Goku raised his head and grinned. Though his face was somewhat pale, his eyes still shone like stars. "I'm fine! Just a little tired. King Kai, thank you for your guidance!"

North Kai looked at him for a long while before sighing. Then he revealed a gratified yet slightly helpless smile. "Goku, you're too polite. Honestly, after teaching disciples for so many years... no, after living for so long, I've never seen a genius like you. It seems my ultimate technique, Kaio-ken, will truly flourish in your hands."

Son Goku scratched his head sheepishly, his tail gently swaying behind him. "It's all because King Kai taught me so well."

"No, no, no." North Kai waved his hands repeatedly, his expression serious as a rare solemnity appeared on his chubby face. "It's because of your own talent, your strength, and your comprehension that you can bring Kaio-ken to this level. If it were anyone else, even if I taught them hand in hand, they could never reach this point on their first day. You... just what kind of potential are you hiding inside?"

Son Goku only smiled and did not answer.

Tenfold Kaio-ken... still isn't enough. On Namek, when I face those true monsters, I have to become stronger. But at least now, I have a trump card.

Over the following days, Son Goku continued training on King of Worlds Planet, consolidating his mastery of Kaio-ken.

With the help of Senzu Beans, the time Son Goku needed to improve his control over Kaio-ken was greatly reduced. To avoid irreversible damage to his body, he used only tenfold Kaio-ken while consolidating it.

North Kai watched him practice over and over beneath ten times gravity, going from onefold to tenfold, then releasing it and activating it again. His movements became more and more skilled, leaving North Kai both gratified and worried.

"Goku," North Kai called out to the resting Son Goku two weeks later, his expression unusually solemn. "You've more or less mastered Kaio-ken. But I have one final technique to teach you, and it is also my strongest ultimate move—the Spirit Bomb."

Son Goku's eyes lit up, and his tail snapped upright. "The Spirit Bomb?"