One Year Earlier
Military Training Base
"Based on current intelligence, Cordyceps spreads in only two confirmed ways…"
In a spacious, tiered classroom, a balding man in his thirties wearing a white lab coat stood at the front, chalk in hand, writing rapidly on the blackboard while reciting the information aloud.
Behind him, rows of male and female cadets sat upright, hands folded on their desks, listening with intense focus to every word the instructor spoke.
"Alright. Now, let's discuss the known stages of Cordyceps infection in humans."
The instructor placed the chalk down, braced his hands on the edges of the podium, and looked directly at the young recruits before him, shifting the lesson to a new, critical topic.
"Stage One of Cordyceps infection: The Runner."
"Typically occurs within one to two days after infection."
"They still retain some human traits—occasionally emitting sounds resembling human voices, and their appearance doesn't change drastically."
"The primary way to identify them is their eyes, which turn completely blood-red after infection. While the fungus affects their vision, the visual system remains relatively intact at this stage. This is actually one of their main methods of locating prey."
"When they don't see a target or detect any noise, they remain motionless, often performing strange, jerky movements. Our research suggests these odd motions may be the result of the host's residual consciousness fighting against the Cordyceps taking control."
"The fungus has hijacked their body and motor functions. The human mind may still be trapped inside, forced to watch helplessly as their body commits atrocities. For them, this could be the most agonizing fate imaginable."
The classroom, once filled with quiet rustling, fell into complete silence. The cadets were visibly shaken by the instructor's words.
They couldn't help but imagine: What if I were infected? What if my mind were trapped while my body harmed others?
Many shuddered, shaking their heads to banish the thought. If that were to happen, they'd rather put a bullet in their own head before turning.
Clap. Clap.
"Alright, focus. Stop daydreaming."
The instructor clapped his hands sharply, snapping them back to attention.
"Everything I just told you could save your lives. If you're ever assigned to external missions outside the quarantine zone, this knowledge might be the only thing standing between you and death."
He erased the board with a sponge, then picked up the chalk again, continuing.
"When a Runner is attacked or detects an uninfected human nearby, the fungus inside commands it to attack. Runners also tend to travel in groups."
"If you're spotted by a Runner, eliminate it before it can make a sound. Once it calls for help, others will come. If that happens, run—find cover before you're surrounded."
"And if other infected stages are nearby, Runners—due to their still-functional vision—will sometimes take on a 'lookout' role. For reasons we don't fully understand, they begin relaying information to other infected, helping coordinate attacks on the target."
"Therefore, if you ever face a direct confrontation with infected, prioritize eliminating Runners. It reduces your chance of being detected."
He picked up a photo of a Runner and pinned it to the board with a magnet, showing it to the class.
The image showed a ragged, disheveled figure with matted hair, head bowed, frozen in a bizarre posture. But the bloodshot, crimson eyes were unmistakable—the very Runner he had just described.
This creature was no stranger to the cadets. They had seen them during the initial outbreak. They knew exactly how terrifying they could be.
Once everyone had studied the image, the instructor returned to the podium.
"Stage Two of Cordyceps infection: The Stalker."
"Typically begins one week to one month after infection."
"At this stage, the fungus has greater control over the host's body. Stalkers are not only as fast as Runners but far more dangerous in close combat."
"As the infection spreads deeper into the head and face, fungal growths begin to emerge from the eye sockets, severely impairing vision. Still, Stalkers retain limited sight."
"Remember: when they're near, you'll hear a distinct hissing sound. They've also developed weak echolocation—comparable to human hearing."
"Unlike Runners, Stalkers don't scream and charge. Instead, they hide, observe their target, and silently follow. When they're close enough, they strike with brutal speed."
"They usually prefer damp, dark environments—like sewers or basements. You won't often see them on open streets."
He picked up a second photo and pinned it to the board.
The image showed a crouched creature, back arched, limbs on the ground like a predator ready to pounce. Half its head was engulfed in mushroom-like fungal growths—a truly grotesque sight.
Then, from his lab coat pocket, he pulled out a small audio device and pressed play.
Hssss…
A chilling hiss echoed through the classroom. Cadets shivered, some visibly tense, even afraid.
"So always stay alert. If you hear that sound, check your six immediately."
He took a sip of water, cleared his throat, and continued.
"And finally… the final stage we currently know of."
He picked up a third photo—not from the podium, but from a folder on his desk. This time, he didn't pin it to the board. He stepped down and walked among the rows, holding it up for the cadets to see.
The image showed a horrifying creature. The body was still humanoid, but the entire head was consumed by bulbous fungal growths. The jaw hung unnaturally, teeth and gums exposed. Even in a still photo, it sent a wave of dread through the room.
"Stage Three of Cordyceps infection: The Clicker."
"Typically occurs about one year after infection."
"And it is, to date, the only infected stage capable of posing a lethal threat to an armed human soldier. "
The room erupted in murmurs. Every cadet wore a look of stunned disbelief. A single armed soldier could easily take down a dozen Runners. Even a Stalker was manageable with preparation. But now they were being told that one Clicker could endanger a soldier's life? It was almost impossible to believe.
The instructor remained calm, unfazed.
"Due to prolonged infection, most of the Clicker's body structure has been transformed by the fungus. Their brain is fully consumed. Compared to Runners and Stalkers, their face is entirely covered in fungal matter, and their visual system is completely destroyed."
"But in exchange for losing sight, Clickers have developed a far stronger echolocation ability than Stalkers. When a Clicker 'hears' movement, it begins to pace the area, 'scanning' every corner and crevice, emitting a sharp, rhythmic click, click, click to map its surroundings—until it locates its prey."
"Additionally, their bodies have been physically enhanced by the fungus. Their strength far exceeds that of any normal human."
"And most critically, once a Clicker identifies a target, it charges with frenzied aggression. The fungal growths on its head can absorb some light gunfire. And they are always surrounded by packs of Runners and Stalkers. If you encounter one—avoid it at all costs. "
He returned to the podium, placed the photo facedown, and refused to show it again.
"Uh… Professor?"
A bold cadet raised his hand.
"If infected people turn into Clickers after a year… doesn't that mean the outside world is now full of them?"
"Ah! Of course not!"
The instructor adjusted his glasses.
"Time since infection is just one basic condition for progression. Whether an infected actually advances depends on many factors. The most important? The original host's physical condition and mental strength. So, Clickers are extremely rare compared to Runners. You might never even see one in your lifetime."
Ding! Ding! Ding!
The class dismissal bell rang from the corner speaker.
The instructor gathered his materials and walked toward the door, not waiting for the stunned cadets to recover.
But just before stepping out, he paused, turned back, and said quietly:
"If any of you ever encounter a Clicker out there… heed this warning: shoot it from a distance, or attack from behind. Never, under any circumstances, engage it in close combat. If you do… you will die a very painful death. "