The Fifth Wave

A week had elapsed since the incident where Heejin summoned the grimoire. Then, without warning, the system flashed another message before the world.

"Damn bastards... They find creative new ways to fuck with us every single time..."

"Ugh..."

"Ooh! That sounds like fun!"

Saebyeok and Jian clutched their throbbing temples in sheer frustration, while Heejin clapped her hands with childlike delight.

"Jian, gather everyone," Saebyeok instructed. "I'll go get Doyoung-hyung and Seoyeon-noona... Heejin, you're coming with me!"

"Aye, aye!"

The mart immediately plunged into bustling, chaotic motion.

Survivors gathered on the first floor around the whiteboard, an area that had naturally evolved into the base's central plaza.

A wave of anxious murmurs rippled through the assembled crowd.

"Everyone saw the announcement, right?"

"Haah... Sixty-six days..."

"That's way too long..."

"Still, the mart's gotten pretty sturdy by now..."

"No way! There are still plenty of holes in our defense. Remember how they breached the rooftop last time? Anything could happen..."

"Right! And the golems don't build siege engines for us!"

"What about the electrified wire fences the mechanics were working on? How are those going?"

"Not well, from what I hear. They're barely scraping by just keeping the fans and basic daily power running. Something about the batteries..."

Anxious chatter crisscrossed the room. Nobody knew what horrors the new wave would unleash. The lone Magic Stone they had managed to scavenge by chance was nowhere near enough to power ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠anything meaningful. And while the mechanics' skills had improved, expecting a revolutionary leap forward under their current circumstances was pure fantasy.

To make matters worse, electrical batteries drained faster and struggled to hold a charge with each passing wave—an unexplained phenomenon that steadily wore down the mechanics. With only two people handling the base's technical demands, their output and pace were inherently limited. Breakthrough ideas to shatter the impasse were nowhere to be found. Everything was in desperately short supply.

Clap! Clap! Clap!

"Settle down, everyone!" Doyoung stepped forward, his steady leadership cutting through the rising panic. "Look on the bright side—the monsters won't be charging straight for our doorstep this time. That buys us much more breathing room than a sixty-six-hour blitz. If we locate the stones quickly and destroy them, we can handle this."

Taking command, Doyoung outlined their strategy. "First, let's clear the perimeter to improve visibility. Saebyeok, Jian... let's mount mirrors along the rooftop edges to watch the alleyway blind spots. And since we don't know where or how these things will appear, let's patrol outward and lay the traps we've prepared—the ones rigged with door chime sensors..."

"Understood," Saebyeok agreed. "Early detection and a rapid-response strike team will be everything. If those stones stack up, we're done for. Seriously."

"Tell me about it... Sigh..." Doyoung exhaled heavily. "It's always one wave after another after another. It wears on you."

"Hey, Hyung, you can't lose heart on us now. We're counting on you!" Saebyeok clapped Doyoung on the shoulder before heading toward the mechanics to collect the sensor traps. "Hyung! Map out trap placements as fast as you can. And during today's scavenge runs, prioritize finding any spare sensors left out there."

"Got it!"

Doyoung turned back to the crowd and began explaining how to set up the improvised chime traps—rigged from convenience store and supermarket entry sensors that chimed whenever an intruder crossed their threshold.

"Damn it... This is terrifying."

"What is? What's wrong?"

Saebyeok had paused midway through setting up a sensor trap, muttering to himself in sudden horror.

"Failing the wave defense is bad enough, but think about the regions where survivors can't destroy the Summoning Stones... where they're left unchecked."

"What do you mean...?" Jian trailed off, looking at him with furrowed brows, waiting for an explanation.

"The condition said 'somewhere within the survivors' territories,' right? What if monsters leak outside? What if they're the breeding kind and establish roots on Earth? And if a sector fails its wave defense and everyone dies, do you think the summoning just stops there?"

"..."

"And this shit is happening all over the globe... The Summoning Stones accumulate. There's no way it'll be the same monster every night either. Why ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠emphasize sixty-six? There has to be a reason... What if their goal isn't just sadistic entertainment, but terraforming Earth's ecosystem entirely?"

"No way... Oppa, don't you think you're overthinking it?" Jian offered gently, trying to soothe the spiraling dread in his voice.

"Hah... God, I hope so."

After finishing the perimeter traps, Saebyeok sought out Eunha, who was busily preparing in her own quiet way.

"Eunha... you can't use fire magic or anything like that, right? Rigging magical traps is out of the question?"

"Um... I don't think I can, Samchon," Eunha murmured softly. "My grimoire is just a basic magic manual... It doesn't cover elemental affinities yet. All it teaches is sensing mana, circulating it, and forming basic mana bolts. That's why Heejin-unni was pouting the other day, asking if there was anything cooler in there..."

Saebyeok turned his gaze toward Heejin, who was lingering nearby. "What about you? Nothing up your sleeve? Shooting flames, freezing things with ice—anything like that?"

"I told you, I don't have anything like that! It wasn't hard, so I just copied what I saw in the book. Mmm... I can read and understand it, but it's not like flashbulbs of inspiration go off in my head. Teehee!"

"Damn it... What am I supposed to do with you...?"

"What's that supposed to mean? For starters, I'm pretty! Isn't looking at my gorgeous face utility enough?"

Looking at Heejin's undeniable beauty, Saebyeok couldn't entirely disagree, but a prickle ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠of exasperation won out, and he gave her forehead a firm knuckle rap.

"Ow! Oppa! You hit me again! See? It's because you keep bonking my head that I can't think of anything creative!"

"Sigh... Jian... take her out!"

Jian promptly clamped Heejin into a playful headlock, wrestled her around for a moment, and then tucked the squirming girl under her arm, carrying her off into the base.

In the distance, the faint, satisfying sound of a firm slap on the backside echoed, followed by Heejin's mock-pathetic wailing: "Unni, spare me!"

Next, Saebyeok checked in with the mechanics.

Unfortunately, there were no miraculous breakthroughs here either. The best he could do was request extra sensor-chime traps and a few more Molotov cocktails. They briefly brainstormed whether physical barriers—like dense thorn hedges or barricades made of piled car wrecks—would hold, but the consensus was grim. Against waves of unknown monstrosities, makeshift obstacles wouldn't buy much time. Moreover, the mechanics reiterated that electrical batteries were draining at an alarming, accelerated rate.

If there was any silver lining, it was their observation that Magic Stones appeared capable of storing energy. While far from a precise scientific analysis, they harbored a cautious, hopeful hypothesis: if Magic Stones could replace conventional chemical batteries, they might serve as a semi-permanent power source.

From there, Saebyeok headed over to Song Gayeong.

"Gayeong, could we plant Soul Trees in a complete perimeter around the mart? You mentioned doppelgängers detest them, right?"

"Yep, totally ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠doable! We'll have to chop down the existing roadside trees, but I can definitely pull it off. I leveled up a ton after the Fourth Wave, you know!"

"Oh, really?"

"I bought extra texts from Shasha and have been studying up. It turns out monsters in general really dislike Soul Trees."

"Oho!"

"Apparently, they radiate a specialized aura... Well, I can't explain it scientifically or anything, but..."

"Hey, that's already huge! Let's get moving right away!"

"Ah! And Oppa... the World Tree has grown so much, you know? Pay a little attention to it, will you?"

"Huh? Aren't you handling it fine on your..." Saebyeok caught himself, swallowing his initial dismissal before softening his tone. "Yeah, fair enough. I've been burying myself in training too much..."

"Exactly! All you do is train, scavenge, and work—you're a total workaholic!"

"Alright, alright, I get it."

"Also, if we can plant the World Tree directly into the soil, this whole area might transform into a Sanctuary. But the requirements are pretty strict. It has to be planted precisely where a ley line flows."

"Do you know where one is?"

"Ah! I only have a vague hunch about whether one exists nearby or not... and even that's a fifty-fifty guess at best."

"Understood... Let's plant the Soul Trees first."

Having completed every preparation they could conceive of, the core combatants of the mart huddled together, racking their brains.

"Hyung, is there anything else we can do?"

"Training?"

"Like survival drills?"

"Yeah, something like that... Running drills so people stay sharp and notice odd anomalies inside and outside the mart could help. And memorizing landmarks to speed up scouting... Ah, we already did that last time, didn't we..."

"...Hyung, really? That's all you've got?"

"Sigh... I don't know, man. The territory we've scouted is just too narrow... We're only out to about three kilometers, right?"

"Yes. But safety had to come first."

"True enough. Manpower is our most precious resource right now..."

"Brother, Sister," Scholar Peter chimed in, offering a serene, pious smile. "Is not the rest in the Lord's hands? Let us pray together."

"Praying... sure, prayer's great. But it feels like there's still something we're overlooking, and it's driving me crazy. Give me a practical idea, Scholar Peter!"

"Ah... then I shall pray with even greater fervor."

"Jesus Christ!" Saebyeok cried, literally calling upon the Savior.

Exhaling heavily, he looked over at Jian. "Jian, how much time do we have left?"

"Ten hours."

"Whew... I'm going to get some sleep. Once the wave kicks off, we'll be pulling all-nighters every night anyway. Better rest while we still can."

It was a privilege earned by being the vanguard.

Jian and Heejin followed him into the tent to rest.

Drifting...

At some point, Saebyeok had developed the knack of slipping easily into light sleep, even if the slightest noise could snap him awake.

In the darkness of his mind, like an old projector suddenly flickering to life, a slightly washed-out image illuminated a familiar location.

What is this? It feels like somewhere I've been before... Where is this?

A strangely recognizable room. At its center stood an unsettling, eerie stone, around which strange mushroom-like organisms were being summoned. The fungi puffed out thick clouds of spores. In response, severed zombie parts littering the pitch-black floor began knitting together—pale mycelial cords weaving limbs and torsos into shape as the abominations dragged themselves upright.

Holy shit?!

"Gasp—!"

Saebyeok bolted upright, his shirt drenched in cold sweat.