Ren Sato woke up to the sound of his alarm and punched his phone until it shut up.
He rolled over and stared at the ceiling, trying to remember what day it was.
Monday.
He groaned.
Ren was a 16-year-old boy with messy black hair and dark brown eyes, tall and lean, with the kind of build that showed he trained a lot. Most people thought he was just athletic, but that wasn't true.
Ren wasn't normal.
Almost nobody knew it, but he could fly. He could control ki. And if he really wanted to, he could destroy mountains.
He just wasn't supposed to.
Only a handful of people on Earth could use ki. Governments knew. Some secret groups knew. But regular people didn't.
To everyone else, Ren was just another student.
"Ren!" his mom shouted from downstairs. "You're late again!"
Ren sighed and got out of bed.
His mom, Aiko Sato, was a woman in her late 30s with short brown hair and gentle eyes, already dressed for work when Ren got downstairs.
"You stayed up training again?" she asked, sliding toast onto a plate.
Ren shrugged. "Couldn't sleep."
That was half true. He trained at night so nobody would see him fly around or blast energy into the mountains outside the city.
Aiko shook her head. "One day you're gonna fall asleep in class."
Ren grabbed the toast. "Wouldn't be the first time."
Aiko pointed at him. "And don't skip school to do your secret martial arts stuff."
Ren smirked. "I never skip."
She stared at him.
Ren coughed. "Okay, sometimes."
He grabbed his bag and ran outside.
The street looked normal. Cars. People heading to work. Kids walking to school.
Nobody knew monsters existed beyond Earth.
Nobody knew fighters strong enough to destroy cities walked among them.
Ren met Kaito at the usual corner.
Kaito Tanaka was a 16-year-old boy with spiky blond hair and bright blue eyes, slightly shorter than Ren but broader in build. He wore his uniform jacket open and always looked ready to fight something.
Kaito was also one of the few ki users.
"You're late," Kaito said.
Ren shrugged. "You're early."
Kaito grinned. "Training after school?"
Ren groaned. "Again?"
"You owe me a rematch."
"You won by ring out."
"A win's a win."
They walked toward school, blending in with normal students.
A group of girls walked past, laughing about some TV show. A salaryman rushed by with coffee in hand. A dog barked behind a fence.
Normal world.
Ren liked that.
It meant people didn't have to worry about the kind of fights he sometimes had.
Then the ground shook.
A deep tremor rolled through the city. Windows rattled.
Students stopped walking.
Cars braked suddenly.
Kaito looked around. "Earthquake?"
Ren frowned. Something felt off.
Another tremor hit, stronger.
Then the sky boomed.
Not thunder. Something heavier. Like air being torn apart.
Ren slowly looked up.
And his heart skipped.
A massive black structure floated high above the clouds.
A giant door.
Flat. Rectangular. Dark as night.
Then more appeared.
Ten in total, spaced across the sky in every direction.
Kaito whispered, "You seeing this?"
Ren nodded slowly.
Normal people around them gasped, screamed, pulled out phones.
"What is that?" someone yelled.
Ren felt something else.
Pressure.
Not physical. Ki pressure.
Something beyond human.
His instincts screamed danger.
Phones buzzed everywhere.
Billboards switched. Store TVs flickered. Phone screens went black.
Then words appeared.
A voice followed, echoing across the city.
"Earth has been selected."
Panic spread instantly.
Kaito muttered, "Selected for what?"
"Ten Doors have arrived."
Ren clenched his jaw.
"Each Door contains a ruler."
People murmured in confusion.
"The Doors will not open on their own."
Ren blinked.
"To challenge a ruler, humans must open the Door by choice."
Kaito frowned. "So they're waiting?"
The voice continued.
"You have one year."
Silence spread.
"Defeat all ten rulers."
Ren felt cold.
"If you fail, Earth will die."
The message ended.
No monsters appeared.
The Doors just hovered silently.
People panicked anyway.
Some cried. Some laughed nervously. Others ran home.
Nobody knew what to do.
Kaito rubbed his neck. "Okay. So that just happened."
Ren stared upward. "Yeah."
Only ki users could feel it.
The power behind those Doors was terrifying.
Way beyond anything Ren had fought.
A commotion nearby caught Ren's attention.
A group of older students argued.
One girl stepped away from them and approached Ren and Kaito.
This was Mika Hoshino, a 16-year-old girl with short black hair and sharp gray eyes, calm and serious. She wore the same uniform but carried herself like she didn't care about appearances.
Ren knew her secret too.
She was strong. Stronger than both him and Kaito.
"You two felt it," Mika said quietly.
Ren nodded. "Yeah."
Kaito crossed his arms. "That pressure wasn't human."
Mika looked at the sky. "No."
Ren asked, "You think those rulers are stronger than us?"
Mika answered without hesitation. "Yes."
Kaito frowned. "How much stronger?"
Mika's eyes narrowed slightly. "Enough to erase cities."
Ren swallowed.
If something like that came to Earth freely, millions would die.
And normal people wouldn't even know why.
Ren asked, "So what now?"
Mika replied, "Someone will open a Door."
Kaito scoffed. "Who'd be dumb enough?"
Mika looked straight at him. "Someone desperate. Someone arrogant. Or someone who thinks they're strong enough."
Ren knew she was right.
Powerful fighters existed worldwide. Some worked for governments. Some worked alone. Some were criminals.
One of them would try.
Mika added, "And when that happens, we'll see what kind of enemy comes out."
A helicopter flew overhead toward the nearest Door.
News reporters shouted through megaphones.
Normal people just saw a giant mystery in the sky.
Only Ren and others like him understood.
War was coming.
Ren's phone rang.
Mom.
He answered.
"Ren, come home," Aiko said immediately. Her voice shook. "Something's wrong."
Ren glanced at Kaito and Mika.
"Yeah," he said softly. "I'm coming."
He hung up.
Kaito sighed. "Man…"
Mika turned away. "Train. Prepare. Watch the news."
Ren asked, "You think we'll have to fight?"
Mika stopped walking.
"Yes."
Then she flew upward suddenly, vanishing into the sky so fast normal people couldn't see.
Kaito muttered, "Still creepy."
Ren looked at the Doors one more time.
They didn't move.
They didn't attack.
They just waited.
Like hunters setting bait.
Ren and Kaito walked home, blending back into normal crowds.
Nobody around them knew the truth.
Earth wasn't ready.
And once the first Door opened, everything would change.
Ren shoved his hands in his pockets.
One year.
Ten Doors.
Enemies stronger than anything humanity had seen.
And only a few fighters stood between Earth and extinction.
Ren exhaled slowly.
Training suddenly felt a lot more important.