A world where monsters and humans coexist.

From mimics that imitate human forms to monsters that lure prey with human voices and mysterious creatures that move only in the dark. To survive in this world, an ordinary human had to follow one single rule above all else.

Never approach an unknown entity carelessly.

However, Toya Aoyagi ended up breaking that rule.

With his hair—a mix of light blue and dark navy—disheveled, Toya was running desperately through a dark alley. The clothes that would usually be neatly arranged were a mess, and his lungs stung every time he inhaled. It wasn't that he disliked exercise, but he wasn't exactly used to running while being chased by a monster.

The incident dates back to an hour ago.

While passing through a closed shopping district, Toya found a lost child. A small frame and a tearful voice. Seeing the child asking for help as if terrified of being left alone, Toya approached without much suspicion. But the moment the child looked up at him, Toya realized something was wrong.

There were no eyes.

Something black squirmed inside the empty eye sockets, and the child's mouth tore open to the bottom of the ears as a bizarre laughter leaked out. It was a mimic imitating a human form. And a highly dangerous one at that, giving its prey no room to escape.

From that moment, Toya's flight began.

"Ha, ha...! Why me, of all things...!"

He heard the sound of something scratching the walls as it followed from behind. He didn't even dare to turn his head. The alleys were intricately tangled, several streetlights were broken, and the darkness of the night was swallowing even the outlines of the road. Toya focused entirely on putting distance between himself and the monster.

However, it was no easy feat for an ordinary human to lose a monster.

The moment he turned the corner of the alley, Toya's toe caught on a stone protruding from the ground. His body tilted forward. He flailed to regain his balance, but it was already too late. Just as orange hair seemed to flash before his eyes, Toya fell flat on top of someone's body.

"Ugh...!"

With a dull thud, both their bodies hit the ground.

Toya froze for a moment, as if he had forgotten how to breathe. It didn't take long for him to realize who he had just fallen on. Beneath him lay a young man with orange hair. Various types of weapons were hanging from his waist, and equipment used for monster hunting was familiarly positioned on his body.

Toya's face turned pale in an instant. He tried to pick himself up hurriedly, but in his panic, his hand slipped, and he ended up leaning against the other's shoulder again. The thought crossed his mind that he might get hit before he could even apologize.

"I-I'm so sorry..."