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In this world, every human possesses the ability to use powers.
But over time, those powers were no longer seen as a blessing… but as weapons.
More and more people began to abuse them — and crime spread like wildfire.
To maintain balance, an elite group was formed: Oza.
Oza are those tasked with stopping the chaos and protecting humanity.
But… becoming an Oza is no easy feat.
Every candidate must go through a brutal selection in a place called Rexium —
a ruthless testing ground where only 10 out of hundreds of participants will emerge victorious.
In the corner of a ruined city, two children sat side by side.
Their faces were dirty. Their eyes had lost their light.
Their parents… had been killed by a power-wielding criminal.
"Renka…?" the little girl asked softly.
"What is it, Vivi?" replied the boy beside her.
"When we grow up… do you think we could become Oza?"
"…So we can protect the people we love?"
Renka looked up at the dark sky.
"I've been thinking the same… Yosshh! Let's make a promise! When we're older, we'll take the Oza exam together!"
Vivi gave a faint smile. "Yeah… it's a promise…"
They were Renka Tsukasa and Vivi Amadeus.
Two children who lost everything in a single night.
Now, all they had… was each other.
But... the world never lets togetherness last for long.
A luxurious car pulled up in front of them.
A wealthy-looking woman stepped out and looked at Vivi.
"You… come with me."
"W-wait!" shouted Renka. "She's my friend! Don't take her away!"
Vivi cried and clung to Renka.
But the woman gently took Vivi's hand.
"Auntie… can't you adopt Renka too?" Vivi asked through tears.
The woman lowered her gaze and softly replied,
"Because… I see an extraordinary talent within you."
"But… you two will be separated someday anyway.
And when that day comes, you must be strong enough to chase after him.
Because Renka… he'll grow into someone powerful. He won't wait for anyone."
Renka stayed silent. His eyes welled with tears.
"Vivi… we will meet again… At Rexium! Don't forget our promise!"
Vivi nodded.
"See you… Renka."
They parted ways.
Fading footsteps… and tears…
But in their hearts, a strong resolve was born:
To become Oza.