The streetlamps flickered violently as distance clashes echoed through the darkness.
"They've already engaged? Weren't they suppoed to wait?" A man said, sprinting down the street.
Another man, Jin Asahi, who was running alongside him, responded. "Yes! I'm not sure what's going on... perhaps the zero engaged first..."
"Well, whatever the reason is, we need to hurry!"
They broke into a sprint toward the clash. When they arrived, they came across three humans wearing aether suits and a mutated human, a "zero" (also known as GEN0).
Those in armored Aether suits were Combat Investigators of GEN1, the world's first anti-GEN0 force.
Jin Asahi and the man alongside him had also worked for the force, but were lower ranked investigators and could only provide support from a distance.
One of the humans were on the ground, with a large cut running across their entire chest. Their facial expression ached with immense pain.
Jin Asahi quickly rushed over and pulled him away from the battle. Whatever this zero was, it had to be at least of the A rank. He reached for a viral tube attached to his waist and poured it down the mans cut. Almost instantly, the cut began to heal itself.
It wasn't magic like what you'd see from one of those fantasy novels. It was made by taking GEN0 regenerative cells, modifying the cell by adding a self-destruction sequence in it, and putting it into a liquid gel form that sealed wounds and self-destructed once its work was done.
"Sir, are you alright?"
The man replied, "Yes, thanks to you. We're not sure why, but this zero knew our location and engaged first. It is an attack class zero and has a ranking of A+. It is known as the Masked Puppet."
"Do you need me to call reinforcements?"
The man hopped up and began walking back toward the fight.
"No, we should be fine. Just stay here, don't get any closer. It has wide range sharp moves like a freshly sharpened sword."
The man got low to the ground before suddenly bolting toward the fight scene.
The zero, Masked Puppet, was covered in a strange robe with a joker mask over his face. It had abnormally long arms, and as he swiped, his arms extended out like rubber and cut anything in its path.
Jin's voice caught. "A+... I've never seen one of these before. It's too strong..."
The man that was with Jin was mortified. It was his first mission since becoming an investigator, and typically trainees and investigators are only involved with C rank zeros or lower.
Jin noticed him and tried to calm him down. "Are you nervous?"
The man rapidly nodded his head, refusing to take his eyes off the scene.
"It's understandable... but don't be, you know those three are combat ranked investigators, right?"
Once again, he nodded his head.
"That means that each of them have fought countless A-rank zeros by themselves. So relax! In fact, one of them, Ren Hoshino, is to be promoted to the specialized investigators rank after this!"
He began to calm down. That's to be expected, there is only around a thousand specialized investigators in the entire world and are capable of taking on S ranked zeros alone.
Moments later, the clashing stopped, and the three Combat Investigators emerged, exhausted.
Typically, even if one is capable of handling zeros alone, it is extremely draining due to their high physical capabilities on top of their abilities.
"Jin, the radio please." Ren Hoshino spoke.
Jin reached in his bag and pulled out the radio, handing it to him.
"Hello, Tokyo HQ. This is Hoshino speaking, Masked Puppet has been neutralized."
Seconds later, a man replied, "Verification code?"
"72AB881"
"Confirmed. Thank you for your service."
"We're heading back now. Please have the recovery unit ready, we're exhausted."
"Understood. Over."
To prevent any zero from faking their deaths or infiltrating the organization, every zero mission is assigned a specific code known only to the team leader. Following the neutralization of a zero, the team leader must report back as soon as possible over the radio and provide the verification code.
Now, why must GEN0 humans be hunted, you ask?
About twelve years ago, a secret society of "GEN0" humans were massacred in a genocide known as the Night of Doom. GEN0 had lived hidden for decades, surviving on human blood and possessing superhuman capabilities. After people began disappearing near their society, the Japanese government investigated and reported it to the UN. Many countries began investigations of their own, and as a result, the UN brokered a treaty toward the GEN0 societies: GEN0 would cease harming humans in exchange for regular blood donations provided by the government.
The treaty had lasted for almost 45 years but suddenly ended when the most powerful GEN0 in history emerged, an SSS rank. He rallied his kind and demanded freedom from humanity's control. He didn't respect the idea that GEN0 was not allowed to interact with human society and was forced into hiding their entire lives in small cities.
They began revolting across the globe, and destroyed cities until their demands were met. In response, the UN formed an organization called GEN1, which was created for the purpose of eliminating all GEN0 across the globe. Almost every country had suffered countless casualties, but because of the discovery of aether, they were able to push back.
In the end, after a brutal campaign that costed 25,000 GEN1 investigators in Japan, they defeated the anomaly and forced the surviving GEN0 back into hiding