Kaito was sweating.
Not the light sweat of a child running around in the park.
This was the heavy, burning sweat of someone who had pushed his body to the limit.
His chest rose and fell rapidly as he leaned forward with his hands resting on his knees, trying to steady his breathing. The evening sun hung low in the sky, casting long golden rays across the backyard training area behind the Amamiya house.
It had been nine and a half months since he started training with his father.
Nine and a half months of daily exercises, balance drills, coordination games, sparring practice, running sessions, and mental discipline.
Nine and a half months of pushing his body further than any normal three year old would ever experience.
And the results were obvious.
Kaito wiped the sweat from his forehead and straightened slightly.
His fourth birthday had passed about a month ago. The celebration had been simple, just the three of them together at home. His mother had cooked an entire table full of food, his father had returned early from work, and they had spent the evening laughing and enjoying the quiet warmth of family.
It had been one of the happiest days of his new life.
But even that night had not stopped the training.
If anything, Daigo had gradually increased the difficulty after that.
Now, looking at himself in the reflection of the training room window, Kaito could see the changes clearly.
His body was still small, still clearly that of a child, but it was no longer soft and fragile. His movements were sharper. His balance was steadier. Even the way he carried himself had changed.
His posture was more upright.
His eyes more focused.
His entire presence felt… brighter.
Stronger.
Daigo had noticed it too.
And apparently decided it was time to push things further.
Kaito heard footsteps approaching across the training yard.
He looked up.
Daigo Amamiya walked toward him with his usual relaxed expression, a towel hanging over his shoulder. The sunlight glinted faintly off his dark hair as he stopped a few steps away.
"Alright," Daigo said casually, wiping his hands.
Kaito immediately straightened.
His instincts had learned to recognize that tone.
Something new was coming.
"We're trying something different today."
Kaito instantly became alert.
The relaxed fatigue in his body vanished beneath a layer of focused vigilance.
He had learned that whenever his father said something like that, the training difficulty was about to increase.
Daigo turned and gestured toward the obstacle course set up across the backyard.
"Come here."
Kaito followed him.
The obstacle course had become a familiar sight over the past months. At first it had looked like a random arrangement of household objects scattered across the yard.
But each part of it had a purpose.
The first section consisted of narrow wooden beams placed slightly above the ground. Kaito had to walk across them without losing his balance.
After that came a series of uneven stepping stones spaced at awkward distances that forced him to carefully judge his movements.
Next was a rope net stretched between two posts that he had to climb across using both his hands and feet.
Then came a low tunnel made from stacked cushions and wooden planks where he had to crawl through quickly without hitting his head.
A small climbing wall followed that, barely taller than Daigo but massive compared to Kaito's size.
After the wall there were hanging rings that he had to swing across.
Then a series of balancing poles.
And finally a short sprint across the yard to the finish line.
The course trained everything.
Balance.
Strength.
Agility.
Stamina.
Kaito had run through it hundreds of times by now.
Which was why he looked slightly confused when Daigo pointed toward the starting point.
"Start from the top."
Kaito blinked.
He glanced at the course.
Then back at his father.
"How is it different?"
Daigo smiled slightly.
"You'll see."
That answer did not help at all.
But Kaito had learned something else during the past nine months.
When his father said start, he started.
Without further questions.
So he walked to the beginning of the course and positioned himself at the first wooden beam.
"Ready?" Daigo asked.
Kaito nodded.
"Go."
Kaito stepped forward immediately.
His feet moved quickly but carefully across the narrow beam. Months of practice had refined his balance to the point where he could cross the entire section without even looking down.
He hopped onto the stepping stones next.
One step.
Two steps.
Three.
His body flowed smoothly through the familiar motions.
He climbed across the rope net with practiced speed, his small fingers gripping the ropes tightly as he pulled himself forward.
Then he dropped lightly onto the ground and crawled into the tunnel section.
His breathing remained steady.
Everything felt normal.
Maybe even easier than usual.
Halfway through the course, just as he emerged from the tunnel and reached the climbing wall—
A flash of golden light exploded from the side.
Kaito barely had time to register it before something slammed into his chest.
Heat.
Pain.
Impact.
"Aaah!"
The scream tore from his throat as his small body was knocked backward off the wall.
He hit the ground with a dull thud, rolling once before coming to a stop on the grass.
The world spun for a moment.
His chest burned.
It hurt like hell.
Not enough to injure him seriously, but more than enough to shock his entire body.
Kaito sucked in a sharp breath.
His mind took a moment to catch up.
Then he looked up.
Daigo stood several meters away with one hand still slightly raised.
A faint golden glow faded from his palm.
Solar beam.
Not strong.
But definitely deliberate.
Kaito stared at him in disbelief.
Daigo simply folded his arms.
"Get up."
Kaito blinked.
"...What?"
"Get up," Daigo repeated calmly. "And try again."
There was no sympathy in his tone.
No apology.
Just a quiet expectation.
Kaito stared at him for another second.
Then he slowly pushed himself up from the grass.
His chest still hurt.
But there were no burns.
No injuries.
Just lingering pain.
He dusted off his clothes.
Without arguing.
Without complaining.
He walked back to the start of the obstacle course.
Then he began again.
This time he moved through the course more cautiously.
His eyes flicked toward his father every few seconds.
Waiting.
Expecting another attack.
But nothing happened.
He crossed the beams.
Stepped across the stones.
Climbed the net.
Crawled through the tunnel.
Still nothing.
His muscles slowly relaxed as he reached the final section of the course.
Maybe that had been the only attack.
Maybe the test was over.
He sprinted toward the finish line.
And just for a brief second, his guard slipped.
Another flash.
Another beam.
"Aaagh!"
The impact slammed into him harder this time.
He tumbled across the ground again, pain exploding across his chest.
This one hurt more.
Still not enough to injure him seriously.
But enough to make his eyes water.
He lay there for a moment, breathing hard.
Then he heard his father's voice.
"Again."
Kaito groaned quietly.
But he still stood up.
He walked back to the starting line.
This time Daigo followed him.
Before Kaito could start, Daigo spoke.
"You need to keep your guard up at all times."
Kaito looked up at him.
Daigo's expression had lost its casual playfulness.
His eyes were serious.
"Right now your subconscious thinks this training won't really hurt you."
He tapped Kaito lightly on the chest.
"Because it's your father teaching you."
Kaito remained silent.
Daigo continued.
"But on a battlefield, that isn't the case."
His voice carried the calm weight of experience.
"You need to be prepared for an attack from anywhere."
The evening wind moved gently through the trees around them.
Daigo's gaze remained steady.
"I know it's not an ideal way to live."
He gestured toward the world beyond the yard.
"But that's the reality of this world."
Kaito listened carefully.
"So from this point onward," Daigo finished, "you should expect pain."
He paused briefly.
"Pain is the best teacher."
Kaito rubbed his chest slightly.
"...Yeah."
He muttered under his breath.
"It is."
Then he squinted up at his father.
"How about I tell Mom?"
Daigo froze.
Just for half a second.
His entire body stiffened.
Then he quickly cleared his throat and straightened.
"You won't."
Kaito raised an eyebrow.
"Why?"
Daigo crossed his arms.
"Because you want to get stronger."
Silence hung between them.
Then Kaito sighed.
"...Yeah."
He stepped back toward the starting line.
"Unfortunately."
He crouched slightly.
"Let's go again."
This time, the moment he moved forward—
Another beam shot toward him.
But Kaito was ready.
His body reacted almost instinctively.
He shifted sideways.
The beam grazed past his shoulder.
His foot slipped on the beam.
For a moment he nearly lost his balance.
But he recovered, arms flailing slightly before stabilizing himself.
Then he continued forward.
Daigo said nothing.
But the faint hint of a smile appeared on his face.
'Good.'
The training continued.
And by the time it finally ended, Kaito felt like he might collapse.
He dragged himself back into the house, took a long shower, and stumbled toward his room with barely enough energy to keep his eyes open.
His muscles ached more than ever before.
But he assumed it was just the result of the new training regime.
The moment his head touched the pillow, he fell asleep.
Instantly.
The next morning came far too quickly.
Kaito groaned softly as he opened his eyes.
Everything felt heavy.
His eyelids.
His arms.
Even his thoughts.
Still half asleep, he slowly slid out of bed and stumbled toward the bathroom for his morning routine.
After brushing his teeth and washing his face, he shuffled down the hallway toward the dining room.
The smell of breakfast drifted through the house.
Kaito walked in with sleepy eyes.
His father sat at the table reading the morning newspaper.
His mother moved between the kitchen and dining room carrying plates of food.
"Good morning," Kaito mumbled.
Akari smiled.
"Good morni—"
She stopped.
Her voice cut off completely.
Kaito blinked sleepily.
His father spoke without looking up from the newspaper.
"Morning."
Akari suddenly said, very slowly,
"Honey..."
Daigo lowered the newspaper slightly.
"What?"
"Look at Kaito."
Daigo glanced over.
Then the newspaper slipped from his hands.
Kaito looked between them in confusion.
"...Okay."
He scratched his head.
"Now what?"
Daigo suddenly started laughing.
Not loudly.
Just a quiet, stunned laugh.
"Look down."
Kaito frowned slightly.
Then he looked down.
His brain took a moment to process what he was seeing.
His feet.
They weren't touching the floor.
They were floating.
Several inches above the ground.
Kaito stared.
Then blinked.
Then stared again.
And without thinking, he blurted out,
"...What the fuck..."