It was already past ten at night.
The television in Mo Chen's parents' bedroom cast a pale, flickering glow across the walls, washing the room in alternating colors that never seemed to settle. Mo Chen's father lay half-reclined on the bed, remote control in hand, flipping channels out of pure boredom. His thumb pressed the button with mechanical regularity—sports, news, drama, variety show—each channel lasting no more than a minute or two before being replaced.
He wasn't watching.
He was killing time.
Mo Chen's mother stood near the wardrobe, arms folded loosely across her chest. Her brows were slightly furrowed, not in anger, but in the way they always were when a thought refused to leave her alone.
After hesitating for a moment, she finally spoke.
"Haven't you noticed something strange lately?"
Mo Chen's father didn't look away from the television. "Strange how?"
"Our son," she said slowly, choosing her words, "he seems… different."
The channel changed again.
"Different?" He chuckled. "You mean more handsome? That I noticed long ago."
She frowned and waved him off. "I'm being serious."
"Alright, alright." He finally glanced at her. "What kind of different?"
Mo Chen's mother took a step closer, lowering her voice as if Mo Chen might somehow overhear them from another room. "I think he's grown taller."
Mo Chen's father blinked, then laughed. "Taller? At this age?"
"I'm not joking." She pressed her lips together. "When we were eating dinner, I stood next to him. He used to be about my height. Today… I don't know. It felt like he was a few centimeters taller than me."
"That's just your imagination," he said casually, switching channels again. "Kids these days wear better shoes."
"I know what I felt." She crossed her arms tighter. "It wasn't obvious, but it was there."
He snorted. "He's eighteen already. How can he still grow?"
"Didn't you hear?" he replied lazily. "People say men can grow until twenty-three."
"That's nonsense," she shot back. "Most men stop growing at seventeen or eighteen."
"Even if he did grow, what's wrong with that?" Mo Chen's father shrugged. "Growing taller is a good thing. Why think so much?"
She paused, then sighed.
"…You're right."
The worry in her eyes slowly faded. Whatever unease she felt lacked a concrete shape, and without proof, it had nowhere to stay.
"Let it be."
Mo Chen's father turned off the television and stretched. "Go to sleep. I don't know why, but I feel unusually light today. Like I can sleep well."
Mo Chen's mother nodded, surprised. "Me too. I feel refreshed. Almost like the last time I felt this good… was after drinking that soup he made."
"The tonic one?"
"Yes. That one."
"I saw him put ginseng or something in it," Mo Chen's father muttered. "That stuff isn't cheap."
"He's wasting money again," she said, though her tone lacked real blame.
Despite their age, Mo Chen's parents were in good health. No chronic illnesses. No serious weaknesses. Because of that, the effects of Mo Chen's Ten-Ingredient Tonic Soup had not fully manifested. Still, it quietly eased the fatigue buried deep in their bodies, lightening joints, smoothing breath, settling something invisible.
They fell asleep quickly.
Peacefully.
Unaware that the cause lay only one room away.
…
Mo Chen, on the other hand, couldn't sleep at all.
There was no tossing and turning. No restlessness.
He simply lay there, eyes open, staring at the ceiling.
'How could I sleep?'
The system existed.
That fact alone was enough to keep his mind racing.
He turned slightly onto his side, one arm tucked beneath his head.
'A system that governs cause and effect…'
'That's not something you casually ignore.'
He wasn't contemplating life in some grand philosophical sense. This wasn't about the meaning of existence or humanity's place in the universe.
This was about planning.
The first priority was obvious.
'Causality values.'
Without them, nothing else mattered.
The second priority followed closely behind.
'Use the smallest possible cause to generate the largest possible effect.'
And that effect had to accumulate, not burn out in a flash.
Mo Chen felt that this second step was far more difficult.
Earning causality values wasn't hard in theory. The world was full of people. Influence one, and you gained a little. Influence many, and the gains multiplied.
The question wasn't whether he could affect people.
It was how efficiently.
Food was the simplest route.
If he used the system to create delicious snacks, stood on the street, and offered free samples, he could easily influence dozens—maybe hundreds—of people in a day.
But the impact would be shallow.
Brief.
Forgettable.
'That's not enough.'
Just as his thoughts spiraled, his phone vibrated softly.
A notification.
He picked it up.
"At 22:30 on August 25, the Meteorological Observatory of our city issued a yellow thunderstorm warning. Thunderstorms are expected tomorrow. Local areas may experience strong winds, hail, and short-term heavy rainfall. Relevant units and personnel are advised to take precautions."
Mo Chen stared at the message.
An idea flickered.
Slowly, he opened the interface of the causality system.
His fingers hovered over the input field.
Then he typed:
[Because Mo Chen blew a breath, tomorrow's thunderstorms and severe convective weather arrived one hour earlier.]
Submit.
A moment passed.
Then the response appeared.
[Insufficient causality value. Please increase causality value.]
Mo Chen frowned.
"Not enough?"
He leaned back, thinking.
An hour was too much. Fine.
He adjusted the cause.
[Because Mo Chen blew a breath, tomorrow's thunderstorms and severe convective weather arrived one minute earlier.]
Submit.
[Insufficient causality value. Please increase causality value.]
Still not enough?
Mo Chen stared at the screen.
'That doesn't make sense.'
The storm was already coming. He wasn't creating something out of nothing. He was only nudging the timing forward.
Yet the system rejected it completely.
After a long silence, understanding slowly dawned.
'It's not about whether the effect is natural.'
'It's about whether the cause makes sense.'
Blowing a breath and altering the weather—even slightly—violated the balance.
Earlier, he had shaken a glass of water and created a hair-styling potion. That had worked because the cause and effect, while exaggerated, still followed a twisted form of logic.
Weather was different.
Nature did not bend to casual gestures.
With a soft sigh, Mo Chen abandoned the idea.
But the failure wasn't useless.
It sparked something else.
'What affects the most people… every single day?'
Eat.
Drink.
Sleep.
Defecate.
Among these, drinking stood out.
Rabbit City relied heavily on the Peach River.
Nearly ninety percent of its drinking water came from there.
Mo Chen's heartbeat quickened.
'If I influence the river…'
'I influence the city.'
Almost one million people.
Even a fraction of that influence would be enormous.
"Alright," he murmured softly. "Let's do it properly."
…
At six in the morning, the sky was still hazy.
The city had not fully awakened.
Mo Chen rose quietly, citing exercise as an excuse, and left the house with a thermos in hand.
Inside it was goji berry water.
Not ordinary goji berry water.
It was water enhanced by the system—ten thousand times its original nourishing effect.
He had spent 4,000 causality values on it.
A reckless investment.
'If this backfires…'
'Well. That'll be interesting.'
The road to the suburban water supply station was remote. No taxis were willing to go that far, so Mo Chen rented a shared bicycle and pedaled steadily for over an hour.
By the time he arrived, his back was lightly damp with sweat.
He hid the bicycle in a grove and approached the reservoir.
The water lay calm.
Still.
This was the source.
Opening the system again, he typed carefully:
[Because Mo Chen poured goji berry water into the reservoir, the goji berry water was fully diluted, and six hours later everyone in Rabbit City was nourished.]
Submit.
[Insufficient causality value. Please increase causality value.]
Mo Chen exhaled slowly.
"Alright."
He revised it again.
[Because Mo Chen poured goji berry water into the reservoir, the goji berries were fully diluted. After twenty-four hours, ninety percent of Rabbit City's population benefited.]
Submit.
A pause.
Then—
[This setting requires 3,000 causality values. Confirm?]
Mo Chen smiled.
"Confirm."
The balance tipped.
The scale moved.
Cause met effect.
And somewhere beneath the still surface of the reservoir, something invisible spread outward, quiet and unstoppable.