Oni Island.
The Biheiru Kingdom, at the easternmost edge of the northern territories.
Further east from there.
Beyond the sea, that island exists.
Oni Island.
A small island known by that name.
It is home to a peculiar clan called the "Oni."
With crimson-black hair and horns upon their foreheads, they are a warrior clan led by a powerful fighter known as the "Oni God."
That is the "Oni."
Though they are a type of demon race, they participated in neither the Human-Demon War nor the Laplace War.
Because of this, they are not considered demonfolk by the people at large, and are perceived much like the long-eared folk or the coal-miners—just another race.
That said, since they rarely leave Oni Island, they are not well-known.
More people have never heard of Oni Island than have.
They are an exclusive, insular people.
Their only human allies are in the Biheiru Kingdom.
Outsiders who trespass into their territory are mercilessly attacked and wiped out.
However, even such a people will open their hearts to guests they have acknowledged.
Even now, one such guest is in their midst.
He had been traveling aboard a ship of the sea-dwelling folk, but when the island drew near, curiosity led him ashore.
After a series of scuffles, he was recognized by the "Oni God" and came to be treated as an honored guest.
He settled into a comfortable life on Oni Island.
With an easygoing manner, he conversed with the Oni God, shared drinks, and sometimes gave training to the young Oni warriors.
He continued this life for about two years.
For a being who had lived for thousands of years, it was but the blink of an eye.
One day, a letter arrived for this guest.
An urgent request, delivered with extraordinary speed by a veteran S-class adventurer.
Its contents were short and to the point: "Found the person we were searching for in the Magic Triumvirate. Heading to the Magic University of the
Upon reading this letter, the guest stood.
Seeing both the letter and the guest's expression, the Oni God asked: "Are you going?"
The guest nodded grandly and replied: "I am. I suppose it's about time."
The Oni spoke up one after another.
They said they'd be lonely.
They begged him not to go.
They told him he could just stay here.
At their words, the guest nodded.
"Nothing would please me more. But human lives are short. If I dawdle, they may well die before I get there. It was brief, but I enjoyed myself. Let us meet again someday."
However, the Oni God—who led the Oni—did not try to stop him.
He said only one thing: "Stay well."
Those words from the Oni God were the final word for the Oni.
Though reluctant, the rest obeyed.
But at least— At least, one last feast.
At the urging of such voices, a grand banquet was held at the Oni settlement.
There were sumo-like bouts between the strongest Oni, drinking contests, and other festivities.
The Oni God and the guest both enjoyed themselves immensely.
And so the guest was sent off with warm farewells.
The good-natured man who had shown up out of nowhere and crashed in the village for nearly two years.
The man who fought the Oni God, was defeated, yet revived the next day, was defeated again and again and revived each time, and before long became friends with the Oni—the undying man.
A towering figure with jet-black skin and six arms.
"Fu ha ha ha ha! Just you wait!"
He pressed on toward the west.
One nation, startled by his sudden incursion, bombarded him with high-level magic.
Another nation, startled by his sudden incursion, scrambled to prepare tribute.
But he ignored them all.
He charged westward as though plowing through.
Through forests, over mountains—at a speed that might outrun the information networks of humankind.
By the time each nation tried to figure out what he was after, He had already passed through and reached the next country.
West, ever westward.
At overwhelming speed.
And at last, he arrived.
"Hmm, so this is the place."
The Magic University.
---
The season was autumn—a bountiful, harvest-season autumn.
This season was extremely short.
But it was a crucial harvest period for surviving the bitter winter, a time when, in a rare treat, festivals were held in town, and for the beastfolk—a season carrying special significance: mating season.
When this time of year rolled around, beastfolk of both sexes grew restless.
The Magic University didn't have that many beastfolk enrolled.
Out of ten thousand students, roughly five percent at most.
Even so, that made five hundred.
Considering the size of the campus, it wasn't all that many.
But during this season, even that small number could be seen dueling all over the grounds.
The duelists were male and female.
During this season, beastfolk dueled with whichever member of the opposite sex they fancied.
After the duel ended, they would spend a few months being lovey-dovey, then marry.
The winner of the duel would become the "boss" of the "family" pack.
Well, supposedly it was "just a custom handed down from the old days."
Linnia and Pursena were the cream of the crop among the beastfolk.
Their combat ability was top-class even among the beastfolk at this school.
And as princesses of the Doldia clan, they were naturally popular.
Following human customs, once they turned fifteen and were considered of age, numerous beastfolk warriors challenged them to duels.
Some had even traveled from distant lands.
Outsiders were setting foot on campus.
Normally, this was something the school should have intervened to stop.
But the mating season was an incredibly delicate matter involving both custom and reproduction.
Banning it outright could have provoked the beastfolk students into a riot.
Therefore, the school permitted non-student beastfolk onto the grounds for "observation," as long as they obtained proper authorization.
Now then—Linnia and Pursena.
Proposing to the two of them and winning the duel would also mean— A shot at the Doldia clan chieftain's seat.
You wouldn't become chief immediately, but when the time came to select the next chief, you'd surely be put forward as a candidate.
Of course, being students far from home, they couldn't simply decide on a marriage partner on their own.
When they turned fifteen, the two of them rejected every proposal.
However, despite this public refusal, the number of beastfolk warriors proposing to them did not decrease the following year.
They were that popular.
Among the proposers, some even tried to force themselves on them, as if creating a fait accompli would make everything fall into place.
Incidents like these led the two of them to hole up in their dormitory during this season.
Turning them down was exhausting.
Even after refusing, "starving males" would sometimes attack anyway.
The women's dormitory wasn't exactly safe, but at least if someone broke in, all the women could band together to drive them out.
So, the two of them stayed in their rooms during this season.
And skipped homeroom as well.
This was probably what you'd call a "physiological leave."
Being in mating season meant the two of them were currently in that state.
Imagining them in their room getting all lovey-dovey—well, it got even me a little riled up.
Though, really, only my head was excited.
A letter had arrived from the two of them, its gist being: "Sorry for the trouble, Boss, but we're leaving the rest to you."
Being told to handle things—I wasn't really doing anything special, though.
Were they asking me to answer roll call for them?
I didn't know which classes they attended, so that was out.
Incidentally, it wasn't only the beastfolk who went into heat during autumn.
And during this season, incidents bordering on rape were rampant at the Magic University.
Perhaps you could call it the downside of having multiple species coexist.
The strict security at each dormitory suddenly made sense.
If both parties were beastfolk in mating season, you could chalk it up to the laws of nature, but there were also cases where first-year students who had nothing to do with any of it were attacked, bewildered and unable to comprehend what was happening.
Of course, rape was prohibited by school rules.
So during this season, guards patrolled the campus.
Rape was not okay, but "consent" achieved through a duel was fine.
However, attacking someone after they had refused a duel was strictly forbidden.
That was apparently how the system worked.
There had been warnings during homeroom and from teachers as well.
During this season, don't go accepting duels thoughtlessly.
Those who lacked confidence in their combat ability should always move in groups.
Fitz-senpai had also expressed concern, telling me to be careful.
"You're strong, so girls might challenge you under the pretext of martial training, but that's a lie. Once you refuse, no matter how much they provoke you, don't accept. Watch your back and leave quickly."
Mating-season girls.
The old me might have dueled them one after another and built myself a harem.
But with this sickly body, all it would do was make things painful.
Mating season.
Had absolutely nothing to do with me.
The only ones involved were those two youngsters over there.
The long-eared girl and the human boy who had become a proper couple.
The eternally-in-heat long-eared girl sitting on the boy's lap, studying together.
Honestly, from morning till night—things were hot and heavy.
Their "heartthrobs" practically drifted all the way over to where I was sitting.
But setting
It would be a bit cruel to let Cliff know that, so I kept my mouth shut..., but frankly, it looked like nothing but an act.
Were those two really okay?
"Master, perhaps you should start on your new creation soon?"
He was operating as usual.
Mating season, what mating season—he was completely unaffected.
"My new creation..."
The other day, I'd started making an 1/8-scale
Since then, my hands had been sluggish.
Was this a slump?
"Right... who should I make, I wonder..."
"Why not distance yourself from people for a change?"
"Then maybe I'll try making a Red Dragon."
"Oh, that's right—you did take one down, didn't you?"
"That was grueling. I thought I was going to die."
"Ha ha ha, you're too humble."
"...? Master, what are you talking about?"
Her cheeks flushed and her eyes sparkled as she listened.
Sure enough, kids in this world loved stories like that.
She wasn't treated all that much like a child, but she was still only six, after all.
"Alright then, I'll make a Red Dragon for you, Julie."
"Hm... M-Master, what about me? Won't you make something for me too?"
"You're my apprentice too. Couldn't you at least offer to help?"
"...! Y-Yes, Master! I shall assist however I can!"
My form was a bit off, but otherwise I was running as usual.
The beginner courses in Divine Strike and Barrier were nearly finished as well.
Next, I was mulling over which classes to take.
Should I go for Intermediate Detoxification?
But I hadn't really run into any trouble with poisons lately.
If the beginner course covered most situations, was there really a need for intermediate and above?
Or should I take Advanced Healing?
That was also mostly handled at the intermediate level, so was it necessary?
Or, since it fell under the summoning category, should I try an Enchantment class?
Enchantment was magic tied to the creation of magical tools.
I didn't know why manufacturing magic was classified under summoning, but trying my hand at a new field couldn't hurt.
Or I could just skip classes and spend more time in the library.
The teleportation incident had hit something of a dead end, but learning the languages of other races might be interesting.
If I wasn't taking classes, maybe I could ask Cliff to teach me Divine Strike.
No, he was too wrapped up in Elinalise lately.
I didn't want to be a nuisance, so I'd leave them be for a while.
Or maybe I should explore fields beyond magic entirely.
Equestrian classes sounded fun, for one.
These were the kinds of thoughts filling my days.
Peaceful days.
--- Or so I had thought.
"You are Rudeus Greyrat—A-class adventurer 'Dead End' who single-handedly slew a stray dragon!
I challenge you to a duel for the right of marriage!"
I was confronted with a duel challenge on my way to the library.
Turning around, what met my eyes was a beautiful girl.
Tanned skin, dark blue hair streaming behind her and gathered at the nape of her neck.
She looked to be about seventeen or eighteen.
Pursed lips, sharp features—the word "gallant" came to mind.
If I had to put a label on it, "warrior woman" would be apt.
Her outfit was dominated by indigo. Did she like blue?
Her chest was... fair enough.
She had a fair bit of muscle, too.
At her waist hung a curved blade—the kind favored by practitioners of the Sword God style.
She wore not a school uniform but a warrior's garb.
The girl was looking my way.
More precisely, with a startled expression, she was looking at the person in front of me.
She was looking at the scruffy, hairy beastman who had challenged me to a duel.
That's right.
The one who had spoken was the scruffy man.
A dog-type beastman, muscles bulging, looking nothing like a magician.
The girl was probably just passing through.
She'd been startled because the massive man right beside her had suddenly blurted something out.
After all, it was that time of year.
She'd probably assumed he was talking to her.
"Um—"
Well, never mind the girl.
The problem was the man.
I was male, and so was he.
This meant I was being challenged to a duel by another man.
This was a serious problem.
"Is this, uh—one of those 'mating season proposal duels' that are going around?"
"Indeed!"
Ugh!
"Sorry, but, you see, despite appearances I'm pretty normal, so the whole man-on-man thing really isn't for me. I'll have to respectfully decline."
"You seem to be under a misconception—"
"Sorry, but I have a piano lesson, so I'll be taking my leave—"
Once you refused, you were not to listen to any more and to leave the scene on the spot.
That was what Fitz-senpai had told me, and I followed her advice.
"Wait!"
Before I knew it, with a thunderous thud, the furry beastman launched himself into the air.
He soared right over my head and landed in front of me.
The leaping power was like that of a reverse-jointed creature.
He could make a fine Dragon Rider.
"You have no right to refuse!
My name is Brukk Adoldia!
I seek to woo Pursena and become the head of the Doldia!"
"Pursena-senpai is on mating leave in the dormitory right now, so take it up with her."
When I said this, Brukk shook his head and bellowed: "I sent a letter to Lady Pursena and learned that you are the pack's boss!
I heard from Lord Gyes of your martial fame!
Of the deed that froze the entire Rain Forest!
Of the feat of slaying a Red Dragon single-handedly!
You possess strength befitting the master of this school—more than enough for me!"
Single-handedly, single-handedly—he kept saying that, but I'd been on foot at the time.
Well, whatever.
"What happens if I refuse?"
"As the pack's boss, you are obligated to accept the duel!"
Let me sort this out.
In short.
The other day, I had defeated Linnia and Pursena in a duel.
After that, they started calling me "Boss."
If one wanted the females under the boss, the proper thing was to defeat the boss first.
And if he defeated me, Pursena would be his prize.
Accepting duels was the pack boss's duty.
I hadn't exactly volunteered to become their pack boss, but apparently that didn't matter.
Animal rules, apparently.
In other words, if I deliberately lost, I'd be stripped of my pack boss status, and Pursena would happily become this guy's bride.
No more duel challenges would come my way.
"It is time... for a fair contest!"
Without waiting for my reply, Brukk let out a tremendous howl and lunged at me.
............
..........
......
Well, that was that.
All bark and no bite.
He charged straight in, got his foot caught in the mud, and I knocked him out with a rock-crushing shot.
Three seconds, give or take.
I'd knocked him out on reflex, but thinking about it, there was no reason for me to deliberately lose.
Pursena didn't seem to intend to marry anyone right now either.
In other words, what that letter meant by "trouble" was probably this kind of thing.
Being pawns in someone else's game rubbed me the wrong way a little, but dealing with opponents of this caliber was manageable enough.
Ah well, fine.
But while I was thinking so lightly of the whole thing, I was attacked five more times on the way to the library.
They acted like they'd been waiting for this day.
Linnia and Pursena—the most popular girls around.
What was so great about them?
Their bodies?
No, there were probably plenty of guys who hadn't even seen their faces.
So it was their status, then?
The first guy had talked about wanting to become clan chief too.
Did they want to be leaders that badly?
What kind of high command were they dreaming of?
However, it seemed there was an established order for who got to challenge me.
One guy who tried to cut in line got scolded for it.
All of it—beastfolk custom.
The beastfolk lived and breathed custom.
Honestly, these beastfolk...
But strangely enough, they didn't venture into the library itself.
Had the school told them not to raise a ruckus inside buildings?
Or was it more beastfolk custom?
I couldn't tell, but either way, time to take shelter for a while.
--- That evening, Fitz-senpai appeared at the library.
"Rudeus, things are getting pretty wild outside. What did you do?"
Her gaze carried a hint of reproach.
"Nothing. Apparently, to marry Linnia and Pursena, all you have to do is beat me."
"What is that..."
Fitz-senpai's brow creased, so I gave her the full explanation.
That I, having defeated Linnia and Pursena, was apparently now recognized as their "boss."
That defeating the boss would supposedly win you the girls.
After I finished explaining, Fitz-senpai looked irritated.
"That can't be right.
You're not the Doldia clan chief.
You may have beaten them in a duel, but you shouldn't have any claim over them."
Hmm... so that was the right take after all.
Of course. If that logic held, I should've been free to do whatever I wanted with their bodies.
"Even so, how are we supposed to make them give up?"
"Huh? Well... beastfolk in mating season don't listen to reason..."
Fitz-senpai rested her chin on her hand and thought it over.
"In theory, you don't actually have to fight them, but they should give up and leave if they lose."
"...So in the end, you're saying I should accept the duels?"
"That's how it is."
She said it so matter-of-factly.
I didn't know exactly how many there were, but about thirty were apparently lined up outside waiting their turn.
Most of them were scruffy men vying to become clan chief.
Defeating every single one of them...
"I'm not looking for that kind of violent daily life."
"I know that. But if you don't do something, you won't be able to leave. If you keep hiding, they might lose patience and force their way in, and if the library gets wrecked, that's a problem too."
"True enough."
Well, I was in a bind.
"A bunch of scruffy men challenging me to duels..."
Who did that benefit?
"Well, it wasn't all men—there was one girl, too."
"Really? Was she cute?"
"Rudeus... are you planning to accept her challenge?"
"Of course not."
Under that reproachful look, I shook my head.
But I was curious about her face, at least.
Where had she heard about me?
"Still, you've got to be curious."
If you knew someone was into you, of course you'd be curious.
Whether I'd actually do anything about it was a matter for after I recovered from my illness.
"Really? Curious, you say?"
...For some reason, Fitz-senpai's mood had soured even more.
She'd told me not to take duels lightly, after all.
Ah, right.
Luke probably had some experience with this sort of thing back in the day, and she'd seen the aftermath.
No wonder she was irritated by my cavalier attitude.
"But with things this serious, can't the student council do something?"
"When it comes to the mating season, there's nothing they can do.
Banning it would only make things worse."
The student council was apparently swamped during this season as well.
Many students went berserk, and some caused disturbances outside the school grounds.
Some used the chaos of the duels to ambush people in the dark.
Student council members were apparently protecting less combat-capable students from such elements.
They patrolled in small groups and intervened on the spot when something went wrong.
Fitz-senpai had stopped by here, but she was about to rotate into patrol duty.
"If the student council is that busy, give me a hand too."
"Rudeus, you can handle this yourself, can't you?"
Today, Fitz-senpai's voice was colder than usual.
Had I said something to set her off...?
No.
Maybe she was remembering that exam from a while back.
She'd said she didn't care that I'd won.
But if I skulked around and hid now, and was seen as a coward who lost, Fitz-senpai's reputation would suffer too.
Fitz-senpai had helped me in many ways.
I didn't really want to deal with this, but for her sake, I'd give it my best.
"Fine. For the sake of Fitz-senpai's honor, I'll slaughter them all."
"D-Don't kill anyone!"
"I know, I know. It was a joke."
Even in a duel, taking a life was out of the question.
That was an unwritten rule.
Still, some strong ones might be mixed in.
I wouldn't let my guard down.
Time to stay sharp.
--- With my course of action set, I headed outside.
What greeted me was an unexpected sight.
"...What the heck is this?"
A large number of beastfolk men were sprawled across the ground.
The phrase "bodies strewn about" was almost too fitting.
Every last one was a beastfolk male.
They came in all sizes.
Their ear shapes varied, too.
Beastfolk came in all kinds, apparently.
Some wore school uniforms, but many didn't.
Oh—there was one girl.
The warrior girl from earlier.
Had she gotten caught up in the chaos?
Or was she into me?
But before I could consider that, a man's booming laugh rang out across the carnage.
"Fu ha ha ha ha!!"
And there, in the midst of all those fallen bodies— A single man stood.
He held the last opponent aloft, laughing triumphantly.
"To think you would challenge me!!
How foolish—yet it seems the Magic University breeds the bold!"
Fitz-senpai and I stood there, dumbfounded.
Because when we stepped outside, this was what greeted us?
Bodies strewn everywhere, with one incredible figure standing amid them?
"Um—"
He tossed the last man aside and turned toward us.
"Oh my—I told you all that if you didn't want to wait in line, you should try defeating me, and you actually did!
Splendid, splendid! I do appreciate those who keep their word!"
Jet-black skin like obsidian—unmistakably demonfolk at a glance. Six arms.
The top pair were crossed over his chest, the middle pair pointed our way, and the bottom pair rested on his hips.
Hair that fell to his waist, colored purple.
"My name is the Demon Lord Badigadi!"
A Demon Lord.
When you said "Demon Lord," it conjured images of kidnapping young girls from nearby villages and having his way with them, or of handling the occasional assassin called a "hero" and then doing whatever he pleased.
Well, never mind that.
The real issue was: Why was a Demon Lord here?
"That foresight of yours—you must be Rudeus Greyrat!
I have heard all about you from my fiancée, the Demon Empress Kishirika!"
He shambled toward us.
And then, in a single proclamation: "I challenge you to a duel!"
Can I offer a cat and a dog as a sacrifice to make him let this go...
How about these alternate subtitles: "Godzilla vs. Rudeus"
"Kamikaze Demon Lord B-Gardie"
"Troubled by Being Surrounded by Puppy Girls!? The Thrilling Mating Season of the Magic University!"
(etc.)