Marcus descended into the mine carrying a torch, followed by several workers. That strange noise earlier had left him both curious and uneasy. What if there was a cave-in or a gas explosion?
"Yuki! Where's that brat?!" Marcus shouted, his voice echoing through the tunnels. "If he ran away, I'm cutting everyone's pay!"
One of the workers protested timidly, "Boss, if Yuki's the one at fault, why cut all of our wages?"
"Shut it!" Marcus snapped, his glare silencing them.
The workers exchanged nervous glances. They were used to Marcus's cruelty, but this time, he looked genuinely rattled.
When they reached the deepest part of the mine, Marcus saw the traces of Yuki's digging. What caught his attention, though, was a strange crack on the wall shaped like a door. He tried pushing it, but it wouldn't budge.
"Strange… I could've sworn there was something here," Marcus muttered as he felt along the wall. "Where the hell is that brat?"
***
Meanwhile, inside the dungeon, Yuki was counting the goblin corpses he had mowed down. His makeshift AK-47 was out of ammo, but luckily, he could craft more bullets from the minerals scattered around.
"Man, this goblin extermination gig is kinda fun," Yuki said, casually sitting atop a pile of goblin bodies. "But… why won't the door open?"
He'd tried going back to the entrance, but the door had sealed shut with glowing words:
[COMPLETE THE DUNGEON TO UNLOCK EXIT]
"Ugh, classic dungeon rules," Yuki groaned.
"Fine, I'll just clear this whole thing."
[FLOOR 1 CLEARED]
[PROCEED TO FLOOR 2?]
Yuki hit YES without thinking. The ground beneath him glowed blue, and he was instantly teleported to the next floor.
***
#Floor 2
The second floor was full of colorful, bouncing slimes that looked like jiggly desserts. Yuki thought they'd be easy to deal with—until one splashed acid on his arm, burning his skin.
"Okay… guns don't work well on slime," Yuki muttered, observing the squishy enemies. "Need another plan."
He remembered every RPG game he'd played—slimes are usually weak to fire or ice. Looking around, he spotted strange cold crystals embedded in the walls.
"Perfect!" He transmuted the crystals into solid dry ice and crafted makeshift ice grenades.
BYUR! BYUR! BYUR!
The slimes froze solid and shattered into icy shards with a single kick.
[FLOOR 2 CLEARED]
"Nice! I'm getting the hang of this," Yuki grinned.
***
#Floors 3 to 7
The next floors were easy pickings:
Skeleton Warriors? He built a flamethrower.
Giant Spiders? He whipped up a batch of ultra-toxic pesticide.
Orc Berserkers? Landmines made from coal dust and metal scraps.
Every monster was obliterated with a mix of modern science and transmutation magic.
Yuki noticed his skill growing stronger. He could now transmute objects the size of a car. His level had jumped from 1 to 15 in no time.
"Guess I really am cut out to be an alchemist," Yuki smirked, tinkering with strange minerals. This time, he crafted a fully functional lightsaber—blue glow, humming sound, the whole Star Wars vibe.
[FLOOR 8 CLEARED]
***
#Floor 9
Yuki's next opponent made him instantly uncomfortable. A succubus—a stunningly gorgeous demoness with… let's just say, very generous attributes.
"Ara ara~ What do we have here? A handsome human wandered into my domain?" she cooed seductively, flicking her crimson hair.
"Uh, miss… I'm just passing through," Yuki stammered, backing away. Sure, he was a normal guy, but this situation was way too weird.
"Oh, don't be shy, darling~ It's been sooo long since I've seen a human. Let's… have some fun," she teased, flying closer with a sultry smile.
"NOPE! BIG FAT NOPE!" Yuki ignited his lightsaber. "I'm still a virgin, and I plan to stay one until marriage!"
"Fufu, you're adorable," the succubus giggled. "But I'm not letting you go that easily."
The fight began—but this wasn't a normal fight. Instead of killing him, the succubus tried to "attack" in ways that made Yuki's face burn red. He ducked and dodged, sweating bullets.
"Why the hell am I fighting this kind of boss?!" Yuki screamed. "Damn you, Zephyr! You planned this, didn't you?!"
Finally, he had an idea. Yuki transmuted rare plants into… extra-spicy KFC chicken.
"Uh, miss? Hungry? This chicken's amazing," he offered cautiously.
The succubus froze mid-attack. Her eyes widened. "W-what is that? It smells divine!"
Turns out, dungeon monsters had never tasted modern food. She devoured the KFC greedily, then clung to Yuki's leg.
"MORE! THIS IS HEAVEN!" she cried.
"Yeah, yeah, I'll make more later. But I can pass now, right?"
[FLOOR 9 CLEARED]
[SUCCUBUS ADDED TO FRIEND LIST]
"Friend list? Is this dungeon a dating sim now?" Yuki muttered.
***
#Floor 10
Yuki expected a fearsome dragon or a terrifying demon lord on the final floor. Instead, he walked into a huge throne room… that was eerily quiet.
On the throne sat a man in his 30s with black hair, wearing a small crown, looking utterly bored. He was tossing a tiny fireball up and down like a kid playing catch.
"Oh, a visitor," the man said dully. "It's been forever since anyone made it this far. Who are you?"
"I'm Yuki. You?"
"I'm Belzebub, Demon King of this dungeon," he yawned. "Technically, we're supposed to fight to the death now… but honestly, I'm bored out of my mind. Been stuck here for centuries."
Yuki raised an eyebrow. "You don't… have any hobbies?"
"Hobbies? What's that?" Belzebub tilted his head.
"You know, fun stuff you do in your free time—like games, sports, whatever."
"There's nothing fun here. Just monsters, rocks, and endless darkness. It's so boring I could die."
Yuki had a crazy idea. Instead of fighting, why not… entertain the guy? He started transmuting dungeon materials into toys from Earth.
"Check this out," Yuki said, holding up an RC car made of crystal. It zoomed across the floor, making little "vroom vroom" sounds.
Belzebub's eyes lit up. "WHAT IS THAT?! IT MOVES ON ITS OWN?!"
"This is called an RC car. Here's the remote."
Belzebub played with it like a hyperactive kid, chasing it around the throne room.
"THIS IS AMAZING! DO YOU HAVE MORE?!"
Yuki made more toys:
A tin-can telephone (Belzebub freaked out when he heard his own voice).
Balloons (he stared in awe at how they floated).
A mini playground slide (he spent half an hour sliding up and down).
A yo-yo (he got obsessed for two straight hours).
Even paper airplanes ("IT FLIES! IT REALLY FLIES!").
"Yuki, you're incredible! Is this all magic?" Belzebub asked, spinning a colorful top with childlike wonder.
"Nope. This is technology and toys from my world," Yuki replied, crafting a kaleidoscope.
"Your world must be amazing. I wish I could go there," Belzebub said with a wistful look. "But I'm stuck as the dungeon boss forever. I can't leave."
Yuki sighed. The so-called Demon King wasn't terrifying at all—just lonely.
"Tell you what. I'll visit often. I'll bring new toys every time," Yuki offered.
"REALLY?!" Belzebub's face lit up. "You'll be my friend?!"
"Yeah, why not?"
[BELZEBUB ADDED TO FRIEND LIST]
[TITLE UNLOCKED: DEMON LORD'S BEST FRIEND]
[DUNGEON CLEARED!]
[EXP +10,000]
[LEVEL UP! LEVEL UP! LEVEL UP!]
***
"Thank you, Yuki! You're the best friend I've ever had!" Belzebub said, hugging him with tears of joy. "As thanks, I'll open a portal straight to the nearest city for you!"
A blue portal appeared beside the throne. Yuki waved goodbye to the Demon King—who was still happily playing with his yo-yo—and stepped through.
***
Crash Landing
SPLASH!
Yuki emerged from the portal… and immediately fell into a sewer ditch.
"OH COME ON! WHY DO I ALWAYS LAND IN FILTH?!" he yelled, climbing out of the foul-smelling gutter.
Looking around, he saw an actual fantasy city—castles in the distance, people in medieval clothes, horses trotting past, even someone flying with magic.
But Yuki's problem? He still wore ragged cloth, was covered in muck, and had zero money.
"I'm high-level now, best friends with a Demon King… and still broke," Yuki muttered, sitting by the roadside.
Passersby gave him disgusted looks, some even tossing pitying glances.
"Back to being a hobo again," he sighed, staring at his reflection in a muddy puddle. "At least I've got OP skills now. I should be able to survive here."
Just as he was about to transmute a stone into gold, a familiar voice rang out:
"YUKI! YOU LITTLE BRAT, THERE YOU ARE!"
Yuki froze. He turned and saw Marcus with a group of thugs, scouring the streets.
"Oh crap, Marcus is still after me," Yuki whispered, panic rising. "Guess he didn't appreciate me ditching the mine."
He quickly ducked behind a trash can, but his rotten luck struck again. His foot stepped on a banana peel, and he slipped.
THUD!
"THERE HE IS! GET HIM!" Marcus roared.
"RUN, RUN, RUN!" Yuki bolted like he was being chased by debt collectors—even though, at this point, he could probably crush Marcus's whole gang.
But old habits die hard. The hobo reflex of running from trouble was still deeply ingrained.
And so, the newly crowned "Demon Lord's Best Friend" found himself sprinting through the city streets like a filthy fugitive, still being hunted by his former boss.
Life, as always, was a cruel joke.