It was the year 2025 AD at the International Space Station. "Tridid...tridit...tridit...cklunk." A hand silenced an analog alarm clock on a table.
"Ugh."
An astronaut woke up, sat on his bunk, and looked outside. He saw the view of a blue planet that felt so close. His gaze then shifted to the alarm clock he had just turned off.
"Oh, it's morning," he said.
He floated down from his bunk, his feet not touching the floor. He retrieved his shoes from the ground and put them on. "Csss." His feet immediately touched the floor once he put on his gravity boots. He then unclipped the belt that had kept him tethered while he slept. The astronaut stood and stretched.
He then walked casually out of the room, drifting down a rotating corridor toward the cockpit. Once there, he sat in the cockpit chair, grabbed a tablet, and started tapping its screen. In front of him was the distant view of planet Earth and the sun.
"Just another routine morning," he muttered while typing.
But then, "grrrk...greeek," he felt the space station shudder. The astronaut immediately put down his tablet and stared forward, his eyes widening as a spinning white dot, like a whirlpool, opened in the vacuum of space directly in front of Earth. The dot grew, becoming larger than Earth and so dazzling it was both magnificent and terrifying.
"Huh, what is that?" he asked.
He bent down, unclipped his shoes, and floated closer to the cockpit's front window. "Grrrrrrk," the tremors inside grew stronger. It felt like the space station was caught in an earthquake. The astronaut's eyes widened at the sight of the phenomenon, which looked like a black hole billions of light-years away from Earth, but what was in front of him was a white hole, spewing out countless celestial objects from within.
"I have to contact central command," the astronaut whispered to himself.
He immediately glided toward the communication console behind the pilot's seat. Without a moment's delay, he sat down, pressed some buttons, and pulled the mic closer.
"Houston, copy... Houston... do you read me, Houston?"
"Teet... teet... teet." An alarm blared and the shaking intensified. The astronaut looked forward, his eyes widening again. "Klotak." The mic fell from his hand, and he was captivated by the strange phenomenon before him.
Slowly, a spherical object the exact same size as Earth, and a matching blue color, emerged from within the white hole, sending a shiver down the astronaut's spine. The shaking in the space station grew more violent, forcing the astronaut to grip the chair to keep from being thrown around. He turned back, picked up his mic, and panicked, unable to comprehend what was happening or what to do. This phenomenon was certainly not on his training list.
"Houston! Do you read me, Houston!" he yelled in a panic.
The astronaut's eyes remained fixed on the Earth-like planet as it fully emerged. The space station was now perfectly positioned between the two blue planets, facing each other. The white hole disappeared, but the Earth-like planet continued to move slowly toward Earth.
"Oh no... that planet is going to crash into Earth!"
The astronaut's fear was confirmed. "Grrrrrrrrrrk." The space station shook violently. The astronaut continued trying to contact central command while watching the approaching planet. As the station was finally sucked in by the approaching planet's gravity and began to enter its atmosphere, "grrrrrrrrrrrrrk...grrrrk," the entire space station vibrated violently and began to burn up upon atmospheric entry.
The astronaut covered his face with his arms and screamed in a panic, unable to do anything else.
"Aaaaaaaaaaaa!"
"Blarrr!"
The space station was instantly incinerated and vanished within the atmosphere of the blue planet that so closely resembled Earth. After that, the Earth-like planet touched Earth, but instead of colliding, they merged. When the two blue planets had completely fused, the newly merged Earth emitted a brilliant light and "blam," a massive ring-like wave sliced through space, as if signaling that all of reality had changed.
***
The whole world descended into chaos. Many cities and even entire countries disappeared as dungeon portals opened, spewing out monsters that defied human logic and had previously been considered mere legends or myths. Of course, they couldn't be fought with regular firearms; even nuclear bombs could only wipe out a portion of them at an immense cost: the total destruction of the country or city that was repeatedly nuked.
After 10 years of fighting and the loss of nearly half of the human population, researchers discovered a change in the human body. The ghost particles known as neutrinos, which had been difficult to study because they never interacted with any matter and simply passed through it like ghosts, were now getting snagged in human bodies. This gave humans various superpowers, depending on how their bodies absorbed them. Not every human was gifted with this ability.
The humans with these incredible, magic-like powers, called Hunters, began clearing the roaming monsters outside of the dungeons and closing the dungeon portals using their powers and weapons created with neutrinos that also took up residence in stones or other solid objects. These objects were called Nether materials. In a short time, they succeeded in defeating the roaming enemies and closing almost all of the dungeon portals, though it came at a great cost.
Humans without powers helped rebuild life under the guidance of the UN, which was now renamed the Nation Of Humanity (NOH) and became the only country remaining in the world. Although, within it, the flags of the USA, China, Russia, the United Kingdom, Germany, Japan, North and South Korea, and several other strong remaining countries were still present.
These super-powered humans were called Hunters and were regulated by an organization under the NOH called the Hunters Association (HA). Life began to return to a semblance of peace, even though dungeon portals continued to open suddenly in the Neopolis capital area—the city formerly known as New York, the location of the old UN headquarters in Turtle Bay, Manhattan—or in other cities.
But as more people became Hunters and passed the tests given by the association, the world entered a truly new normal. The opening of dungeon portals was simply a part of this new normal, even though researchers continued to investigate what the dungeons actually were and what their purpose was. Now, dungeons were even used as a benchmark for Hunters who wanted to test their strength or show off for fame.