Breakthrough with the Forbidden Master

Both my parents were commoners.

It seems they were childhood friends who attended the academy together, then were both chosen as members of the Hero party…… Well, some things happened, they got married and I was born.

In a word, this elegant mansion was built after their marriage.

And, there is a spacious exhibition hall in which a lot of weapons and magical tools both ancient and modern are usually locked.

Inside, there are swords and armor that are placed in a showcase or displayed on the walls.

It is probably as a hobby that my father, a magic swordsman, acquired numerous weapons after marriage.

He claims to have mastered all kinds of martial arts, but I’ve never seen my father use a Spear or a Halberd before.

However, there in the far end of the armory-like exhibition hall, there is a foreboding thick door.

It is a space that can only be opened once a year, wherein lies the treasure which changed the history of the world and saved humanity.

“Now then, Little Man. While I retrieve some rags, do go inside and reclaim your childhood. If you want to steal it, please do your best. Well, it’s impossible for a half pint to pull out the sword that’s sealed on the pedestal.”

“I’m not stealing it! It’s… well…… I wonder what it will be like to see it now….”

Sadiz tells me with a smile. I felt awkward, but I unlock the door with the key I received.

The room within spreads out to a perfect square floor.

On the floor a pentagram magic circle is drawn, and in the center is a sword stuck in a pedestal.

“…… The Sword of the Hero…… The strongest in the world… Hmm?”

A room that is only released once a year. I wasn’t here last year or the year before, so I’ve come into this room for the first time in a few years and looked at the sword…

“…… Huh?”

Instead of the sword, I was looking at something else.

『Hmm… the door opened… I see, tis been a year… how many now… about 15 times…』

It’s not my own words. There should be no one within the sealed room because it is usually locked and no one can enter.

But before I entered, there was already someone there.

『…… Hmmm!?? This one… ah…… Hiro’s progeny… was but a toddler, but now a little grown-up and resembles Hiro.』1 

“No, who are you!! Why are you here?”

『…… What?』

Wait, why are you surprised?

Moreover, he’s not human!

Long, silver hair. Sharp and majestic devil horns that extend from the head.

The medieval beauty form that could be as both man and woman with a suspicious pattern engraved around the eyes.

A mysterious demon dressed in a purple robe that covers the whole body.

I raised my voice and prepared myself.

『…… Oi…… well, I never… child…』

“Heh!?”

『Can you hear my voice? Do you recognize my presence?』

“W-What the hell are you saying! Wait, how did you get into this room? Are you a demon? A robber!?”

『What!? How has this occurred… by no means….. has something changed in my fifteen years of solitude?』

Fifteen years? What’s this guy talking about? No matter how you think about it, he doesn’t seem to be tangible, and yet I feel a strange presence.

This guy isn’t normal!

“Little man… you’re noisy. Did you actually try to pull out the sword?”

“Sadiz! Watch out, there’s some strange guy here!”

“……?”

At that time, Sadiz heard the commotion and came in holding some cleaning supplies.

There is no a problem with this.

Although Sadiz is a maid, she has graduated from the Academy with excellent grades and is qualified as a 【Superior Warrior】.

I don’t know why she is content with being my exclusive maid, but when I was a kid, she was as talented as my personal escort.

With both Sadiz and I, no matter who this guy is, he’s…

“Little man, there’s no one there…”

“Eh?”

“…… You’ve been a virgin for so long that you’ve finally started to hallucinate with your delusions… Oh dear…”

I was surely able to see the demon within the sealed room, but the fact that nothing was visible to Sadiz shocked me .

“Eh? What, why? He’s there, right?”

“Lil’ Earth, please give up on this strategy. Trying to scare me into pushing you down to get intimate is meaningless. So, please remain a virgin for a while longer.”

“No, no, it’s not that!!”

“Well, I still have preparations to make. Please don’t make too much noise, Little man.”

She really can’t see him? Sadiz left in preparation for cleaning again.

『…… Apparently…… the only one that can see me… child… is you …』

“Wha…!?”

『Even so…… When I had a body, I had lived for tens of thousands of years, but… it brings me some joy to have a conversation with someone for the first time in a dozen years… I am frail… under the circumstances I would lose to humans….』

Is he stupid? No way, I’m the only one who sees him?

『Confined to this cramped space… the only intrusion is during the yearly cleaning… for such an occurrence, what does it mean? Mischief from god? Well, either way… tis all about you… my instinct tells me. Even though I was obsessed with this sword, but… child, you are curious as well!』

“What, what…”

『Tis ironic, but… in a sense, a stroke of good fortune. I could see nothing of the outside world because this sword had not left this room since I was overthrown. Huhahahahaha!』

“Uh, W-What is this? Hey, what the hell is with you!”

Then, the demon approached me, trembling with a smile mixed with ecstasy and madness.

“Stay away! No matter who you are… I know you’re listening! You wanna get beat up!”

I picked up the mop that Sadiz had placed in preparation for cleaning.

I held it like a sword, further increasing its power by imbuing lightning magic that I excel in.

『Hoh~… 【Magic sword】… but…… tis unrefined…. mediocre… a far cry from Hiro’s prowess.』

“Heh!? Y-You…!”

I was so engrossed that I swung at the demon. However, the demon, who I thought got hit, without doubt slipped through my attack.

『Tis no use. Your attack is meaningless to a spiritual body. However, tis you who is fortunate as all that remains is a spiritual body.』

“What the…!?”

『With this level of magic sword, even if you train for a hundred years, you would not even be considered an enemy during the era I was active.』

“…… wha. …”

『No matter, you shall be in my care from now on. I shall give you my name.』

I threw up as the demons looked into my eyes.

『I am ‘The Great Demon King Tre’ainar’…… he who once sought to conquer the world, but was slain by your father and his companions.』2

“Huh!?”

『The modern world that was lost to me… I shall see it through you, child.』

And then, I lost consciousness.

[S1] Enter the Great Demon King! I decided to have him use a more sophisticated speech pattern. Light Shakespearean speak (like using “tis” instead of it’s) and more high born vocabulary. So yeah, to the THESAURUS!!!

[S2] Ooooh $%#@! Here we go again! The Great Demon King, the titular “Master” is literally named “Trainer”. So I played around with the name to make it look more foreign!