The Giant Forest, Rudoa, located in the empire’s most northern region.
“The undead dragon’s 3-minute cooking~!
First we start with~ the bittersweet taste of rotten flesh! ♬
Here’s the corpse of a dragon♪” a man sang. He wore a black suit and a silk hat, and as he raised his right hand, the lovely corpse of a blue-scaled dragon, several dozen meters in length, spilled out from the ground.
“Add salt, pepper, and a pinch of sugar to the corpse♩”
The man took out several spices from his pocket and sprinkled them over the corpse.
“Boil at 100 degrees♪”
A poisonous-looking purple liquid enveloped the dragon’s body and soon began to boil.
“Wait three minutes, the rest is omitted—and hurray, the dead dragon is finished♫”
Its eyes melted, and a red-black light flashed deep in its eyeballs as the lovely blue dragon slowly awoke.
“You’ve got bad taste as usual,” said a man with a monocle and black hair that blended into the shadows. He rested his back on a large tree and yawned loudly.
“Ah, Raazucchi. Thanky thanky for this dragon-chan♫ It’s the best kind of dragon—so spunky it makes me hard. ♪”
“Do you need to go so far against these humans (pieces of trash)?”
“It’s obviously feed for those worms pretending to be heroes and not for you little ants. ♬” An unbearable raging hatred flashed through the man with a silk hat’s eyes.
“You think they’ll just come out?”
“According to Grim they will♩”
“Then hurry it up. I’m almost at my limit.” The black-haired man’s eyes and hair flared red and the air warped with a plosive sound as a thick red aura gushed out from his body like a muddy stream.
“Oh scary, scary ♬ Don’t worry, those insects can’t stand up to the 10,000 undead and this undead dragon. Those pieces of trash will poke their heads out without a doubt.”
“And if they don’t?”
“U~mm. Maybe I’ll have the empire destroyed♡”
“Fine. You’ve gone out of your way to move me. If you fail my expectations, then—” the black-haired man disappeared before finishing his sentence.
“Now, everyone~, it’s time to wake up! You’re hungry, right? Absolutely ravenous, right? While you gobble this up… And, forward! And, forward!”
From the surroundings of the black-haired man with a silk hat, the undead dragon and dozens of skeletons, zombies, and liches crawled out.
The myriad of undead formed a file and marched south into the forest.
 Here’s a wiki article about this sound if you’re not familiar already.