Dragon King Mountain lay in the kingdom's northern reaches, rich in rare ore and danger alike.
True to its name, dragons dwelled there, their aura warping nearby monsters into stronger, fiercer forms.
Even so, a town had sprung up at the mountain's base, thriving despite the peril.
On the road from that foothill town to the royal capital, a single knight now fought for her life.
"Damn it! It flew away again!"
Grace gritted her teeth, glaring at the dragon circling above.
It was one of the Dragon King's own brood—and it had chosen her as prey.
"Enough, Grace. Fall back."
"Your Highness! I told you to stay hidden!"
The voice came from her master, Prince Heinz.
The handsome young prince, usually the envy of noble ladies, now stood pale but resolute.
"My legs won't outrun that thing. But you can escape."
"Don't be absurd! No knight abandons her lord. Even if I survived, I'd be dead in name and honor both! Do you wish me to die, Your Highness?"
"I do. Die as a knight—and live as a woman. ...There's someone you love, isn't there?"
Grace froze.
Heinz smiled faintly, as if the dragon above no longer mattered.
"...Your Highness?"
"I'm sorry, Grace. You were my milk sister, yet I bound you to me as my knight.
I was selfish—too cowardly to confess, too greedy to let you go. But now... at last, I can stand as a man, not a prince."
He smiled again, gently prying the sword from her hands.
"Go, Grace. I'll buy you time. Live—for the man you love."
"...Your Highness..."
He turned his back to her and walked toward the dragon.
Grace could only watch, trembling, as her prince faced death head-on.
He had always smiled at her reckless ways, called her troublesome but precious.
He was her lord, her brother in spirit—her irreplaceable light.
"Your Highness... Your Highness!"
Her scream echoed across the mountain road.
* * *
"Oh my, Grace? What a coincidence."
"...Huh?"
Grace spun at the voice behind her—and there stood Onee, wearing his usual too-tight tunic, a heavy leather pack slung over one shoulder.
"Yuuki-dono!? What are you doing here!?"
"What do you mean? Dragon King Mountain's a top-tier spot for adventurers. But wow, the monsters here really are tough. When I ran into a basilisk and my lower half turned to stone, I got a little worried."
Apparently, "a little worried" was how Onee described partial petrification.
If asked how he recovered, he'd probably just say, 'With sheer willpower.'
Nothing in this world could stand against Onee's blazing passion.
"What about you, Grace? Wait—hello, handsome."
"Wha—!?"
Noticing the prince facing the dragon, Onee's eyes sparkled.
Grace panicked, doubly so—one danger from above, one from beside her.
Even if the prince survived the dragon, would he survive Onee's interest? (In a very different sense.)
"Wait, Your Highness!?"
As they spoke, the dragon dove toward Heinz in a blur of wings.
Even with sword training, he didn't stand a chance.
"Yuuki-dono! Please, help—!"
Grace turned, desperate.
But Onee already had his back to the dragon, holding a rock in one hand, his body twisted into some bizarre pose.
"No more—Hi○-oh!"
With a nonsensical shout, he spun and threw.
It was a perfect tornado pitch—though no one from this world could possibly know that.
Modern Japanese kids probably wouldn't get the reference anyway. Revealing it might give away Onee's real age.
"Wait, he's using a rock—?"
'GRAAOOOAAAHHH!?'
"Whaaaat!?"
Grace could only stare as the stone slammed into the dragon's skull. The impact split the air, followed by a dying roar that shook the valley.
Never underestimate a rock.
Back on Earth, a certain shepherd boy once killed a giant with one, and Onee's spiritual cousin, Cú Chulainn, made quite a name for himself doing the same.
High killing power, long range, infinite ammo—rocks are humanity's first and finest weapon.
"Oh? Out cold after one hit? How disappointing."
Grace just stared. The dragon had crashed to the ground, completely still, while Onee twirled another stone in his hand, looking bored.
Grace had known Onee was strong—but enough to kill a dragon? That was absurd.
For context, slaying a dragon alone would earn anyone the lifelong title of Dragon Slayer.
And in that moment, Onee's name was forever etched into this world's history.
"What... what just happened?"
"Y-Your Highness!"
Grace rushed toward the prince, who—thankfully—was still breathing.
"Grace... seems I've failed to die. Did that one save us?"
"Yes. He's an adventurer named—"
"An honor to meet you, Your Highness. I am Yuuki Kokushou."
"...What?"
Onee knelt gracefully, introducing himself like a knight before his king.
For all his flamboyance, he was still Japanese at heart—well-mannered when it counted.
Grace could only gape. She'd never seen Onee act like this before.
And, if she was honest, the cool, gallant act was... kind of attractive. Not that she'd ever admit it.
"Kokushou-dono... I've not heard that name."
"My homeland lies far beyond this kingdom. It's only natural you haven't."
"From a foreign land, then... I see."
The prince cast a meaningful glance toward Grace.
She froze. He knows. Oh no, he knows.
"Kokushou-dono, your skill was remarkable. Would you consider serving me as a knight?"
"Wait, what—!?"
Grace panicked behind him, gesturing wildly, but Heinz was already digging his own grave.
Still, she reassured herself—Onee wasn't the type to accept anything that formal.
"...It would be my honor, Your Highness."
Why!?
Grace screamed internally as the two men proceeded with a swift, impromptu knighthood ceremony.
Her sword served as the ceremonial blade, and with Onee's composure, the scene almost looked dignified.
"Yuuki-dono... why did you accept?"
"Well, lately everyone's been pestering me to join the kingdom. When the prince himself asked, even I couldn't exactly say no."
Apparently, the crown had been trying to recruit Onee for some time.
He'd dodged every offer until now—but with the prince's direct request, even he couldn't refuse.
"Don't worry," Onee added with a teasing smile. "I'm not planning to seduce the prince or anything."
"I—I see..."
That at least brought Grace some peace. Surely, Onee wouldn't fall for royalty.
"...But I can't say the same for some of the other handsome knights around here."
Whether it was fortunate or not that Grace didn't hear that muttered line—well, that's anyone's guess.
For now, peace had returned to the otherworld.
* * *
"...So he actually killed a dragon."
"...He did."
Meanwhile, in Takamagahara, Amaterasu-sama and Tsukuyomi-sama watched the scene unfold, speechless.
"Maybe it was just a big lizard pretending to be a dragon?"
"No, that was a true dragon species."
For the record, dragon species are revered as gods in some realms—creatures on par with giants, capable of challenging the divine.
And Onee had felled one with a single stone.
At this point, it's safe to say there's no being left on Earth—or any world—that can rival him.
"...If Susanoo hears about this, he'll pick a fight for sure."
"Please don't let him. The otherworld would end up a wasteland."
At this stage, Onee wasn't so much a person as a natural disaster.