This was the Demon King's Castle.

　It was also the headquarters of the Demon King's army, and as soon as the previous Four Heavenly Kings returned to this fortress, Granberza shouted out loudly, "Bashbarza!

''Bashbursa!　Where is Bashbursa!

　Even the soldiers, generals, and servants packed into the Demon King's castle reacted to that loud cry, and they trembled.
　They were not shouted at themselves, but they stiffened with fear.

　Grumberza's loud voice, which was claimed to be the strongest of all time, had that much power.
　He is a man of ability who can kill people with his voice alone.

　Anyway, we pushed through the castle and arrived at the back room.
　It was a private room that Bashbarza occupied exclusively as the Four Heavenly Kings.
　Such privileges are allowed because it is a position that should be the pinnacle of the Demon King's army, but as for Bashbarza, those specially allowed things might not be allowed even today.

　He kicks down the door without knocking.

　A single figure floats in the room, cluttered with books and magical laboratory equipment.

''Well, well, well, Father. What's going on here all of a sudden?'

　Bashvaza, one of the current Four Heavenly Kings.

　His appearance had changed so much that it was almost as if he was a different thing than what I had seen in the past.
　He had lost a lot of weight.
　His flesh had become thinner and his cheeks were smudged, and his eyeballs were hollow and scurrying.

　Its undead-like appearance frightened even his own father, Granbaza.

''Bashburza........is that it?　Are you really...?
''Hahahaha. Oh dear, isn't it terrible to forget your face, no matter how disappointing your son is?　....Huh?　If you look closely, my compatriot, Zebiantes of the Four Heavenly Kings 'Huafu' is with you too, right?　It's a rare combination.

　Zebiantes is dragged away from the Mithril mine.
　I finally get Grumberza to let go of his grip on my neck and fall to the floor.

''Geez, what...?

　Since Zeviantes is a free spirit by nature, he doesn't want to get involved in this acrimonious confrontation between father and son.
　But if you run away, it will be even worse the next day. I'm not going to be able to get rid of it.

The only thing you need to know is that you can't get away.
'What is it?　You and I are the Four Heavenly Kings and we are kindred spirits. You have nothing to hide!

　The magnanimity that is unimaginable from the usual Bashbarza makes it more eerie than ever.
　Thanks to that, instead of Zebiantes, who was immensely disappointed, Grambarza opened his mouth again.

''.........Bashbarza, have you entered the 'secret room'?''
'The Chamber of Secrets'?　What's that?

　The fierceness of the father's spiritedness released by the son, who is so blatantly in love with him, increases.

'Usososo, I know. I can't afford not to laugh at a joke like this.
Then tell me, what is the 'Chamber of Secrets'?
'A room somewhere in the Demon King's Castle. But I don't know where it is. We'll never find it by searching for it, but we're certain it exists.

　Bashvaza replies cheerfully.

However, the greatest significance of the Chamber of Secrets lies within it. That room holds all the forbidden curses that have been developed in the past.
That's why we don't know where the Chamber of Secrets is and no one can get to it, because we are not allowed to touch the d*mn thing without permission. It's because we're not allowed to touch the forbidden curse without permission.

　My father, Glamberza, takes over the explanation and says

'A forbidden curse is a masterpiece and a failure created by past magical developments. It is very powerful. It is far more powerful than the new magic that was created as a success story. But it came with a terrible flaw, as if it was the price, and was sealed because it was too dangerous.

　That's the forbidden curse.

　The mithril compression magic bombs that Bashverza had once attempted to produce were also both powerful and flawed magic, but they were not a forbidden curse.
　This is because the flaw of consuming large amounts of mithril in its manufacture was not considered dangerous enough to be designated a forbidden curse.

　To be a forbidden curse, it had to be even more frighteningly difficult to handle, and the amount of damage it could cause if mishandled.

　If it is mishandled even a little, the demon race itself could be destroyed.
　If it weren't that dangerous, it wouldn't be called a forbidden curse.

That's why the 'secret room' is considered a secret place where no one can enter. Only those with limited authority are allowed in. Who has that authority is.........!
The Four Heavenly Kings.

　There was a violent spark between father and son.

''You know ... Bashvaza, you know?　One of the forbidden spells is the use of magic to subdue magical beasts.
'Isn't that great magic!　If you can control the monster beasts as you wish, the heroes would have a twist, so why did you forbid it?

　The reaction was too deliberate.

I'm sure you'll be able to find out more about it. The magic of a demonic beast emissary is precisely the magic that mixes the consciousness of the magician and the consciousness of the demonic beast.

　The magician and the hexenbiest share consciousness, and the hexenbiest moves according to the sorcerer's desire.
　A magical beast kills what the sorcerer sincerely desires to kill.
　The magical beast destroys what the sorcerer sincerely desires to destroy.
　This is the system of the magical beast messenger, which projects the sorcerer's desire onto the mind of the magical beast.

"There is no other way to move a demonic beast, an absolute powerhouse that far surpasses the demon race, as desired. Brainwashing magic that can control a bat or a rat would only be instantly played against a demonic beast.

　That's why controlling a magical beast doesn't involve controlling it, but rather overlaying its mind and making it one with it.
　And that action carries an uncommon risk.

In the first place, eliminating the boundaries between self and others and mixing their minds together is dangerous magic. What is mixed up cannot be separated, and consciousness without distinction will become meaningless and obsolete.

　And what happens if you mix your consciousness with a monster beast that far transcends the demon race?

''The spirit of the sorcerer will be swallowed up by the spirit of an even bigger demonic beast and become crippled. If that's all there is to it, it's still fine. But the demonic beast would dutifully fulfill the wishes of the sorcerer who took it in and destroy everything the sorcerer wished to destroy.

　Hundreds of years in the past, the demon race was once nearly destroyed by it.
　Unlike normal emissary magic, since the sorcerer had become a cripple, he couldn't stop with reason, and the demonic beast wouldn't stop until he had destroyed everything.

　Until it destroys everything that the sorcerer once hated.

Do you know how horrible that is?　The forbidden curse is forbidden because it can never be touched!　Not being able to understand its meaning and using it easily is an indiscretion that should not be reserved for the Four Heavenly Kings!　That alone is enough of a reason for dismissal...!
''Don't bother!''

　A rebuttal that pierced my eardrums echoed through the room.
　It was the first time in my life that I had ever cursed Bashbursa, my too-great father Granbursa.

'What was that just now?　Forbidden spells are scary, and demonic beasts are scary too. You're right!　But how could you tell me that?　It's none of my business!　I don't know what you mean!
You used that curse on me.
That's a terrible accusation!　Why do you think that's a terrible accusation?　Do you have any proof?
The rapid deterioration of your health. Your rapid decline and your severe emotional instability. It's all due to the fact that your mind is one with a hexenbiest, right?

　By merging their spirits with those of a hexenbiest, the ferociousness of the hexenbiest will infect the sorcerer as well.
　As a result, the sorcerer has become just as ferocious as the hexenbiest.

In addition, the sorcerer releases an excessive amount of magical power in order to stop the mental erosion of the monsters. The end result is exhaustion and emaciation. Just like you are now.

　The cheeks are sunken, the eye sockets are hollowed out, and Bashbarza has the appearance of a ghost.

The best part is the place where the demon beast appeared. I've heard about the feud between you and the Mithril mine. You must really hate that place that was the cause of your fiasco.
..........
''The manipulation of demonic beasts is not easy. Due to the characteristics of the messenger law, it only breaks what the surgeon really wants to break. In the first place, the suspects are narrowed down to the Four Heavenly Kings when they are allowed into the 'Chamber of Secrets'. Among them, the one who harbors the utmost hatred for the Mithril Mine....

　Bashvaza is all I have.

''........Foolish son. He probably thought to recover from his repeated blunders in one fell swoop by the terrifying power of the Flame Demon Beast anyway. But that idea in itself is a disqualification for the Four Heavenly Kings.

　I'm allowed access to the forbidden curse site to keep it under tight control. The manager himself uses the forbidden spell to make a profit.

"I can't leave such a selfish person on the throne of the Four Heavenly Kings!
Shut up!　Shut up!　Don't bother me, old man!

　Bashbaza had a dangerous light in his ghostly eyes.
　They were no longer the color of sanity.

''Four Heavenly Kings disqualified?　I hope so!　I'm not interested in the Four Heavenly Kings anymore!　I'm going to ascend to a higher and even greater position than that!

　Bashvaza smiles proudly.

I'm going to be a hero!　Kill the brave, destroy the human race, accomplish feats no one has ever accomplished before, and become a legendary figure that will never go away!　Use the power of the Fiendish Beast Salamandra!
Finally, you spit it out with your mouth. ...Zebiantes.

　Glamburza, looking around at the current Four Heavenly Kings who are frozen at his side.

'You heard that word again, didn't you?
''Yes, yes...?
The current Four Heavenly Kings, Bashvaza, have committed a grievous treason. For bringing forth a forbidden curse that must be strictly controlled, and for endangering the demon race itself.

　A curse is something to be feared so much.


"Kukku is going to execute his own son?　How can you be so heartless, Dad?　........But which one of us is in rebellion?
"?　What does that mean?
''The old bastard knows a lot about the forbidden spells of the magical beasts, but I guess there are things he doesn't know strictly because he hasn't actually used it.... For example, a sorcerer who shares his consciousness with a hexenbiest can also share his senses with the hexenbiest!

　Bashvaza tugs at his lower eye lid with his finger to show off the fact.

''What the Flame Demon Beast Salamandra saw is that I can see it with my own eyes. I could clearly see you at the foot of the Mithril Mine, where you were standing side by side with the brave man who was supposed to be your enemy, and I could see you clearly too.
Do you think that you knew all along and...?
What greater betrayal is there than cozying up to an enemy, right?　Disloyalty?　An informant?　Anyway, it means that the legendary hero Granberza has also fallen into the hands of a filthy traitor. Gyahahahahahahahaha!

　Bashbarza laughed as he bent over as if his spine was about to break.

'Great!　My luck is finally turning up for me.　The current heroes and the previous heroes are all gathered in the same place!　Kill one of these in one fell swoop and it's a big deal!　And then the previous Four Heavenly Kings who became traitors will be executed as well, and any extraneous parallels will disappear!　It's enough for me to be hailed as a hero by myself!
Bashbursa!　It's too disgusting!
Zebiantes!　You were with a brave man, and I had a perfect view of you!　I'll execute you for treason too, don't worry!

　And one more.
　There was another person there who could not be overlooked by Bashvaza.
　The one person who was more important than anyone else, the one he hated the most.

"Dariel........Dariel Uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu!

　He had confirmed that figure as well.
　Through the eyes of the demonic beast that shared his consciousness, he could clearly see it.
　He himself banished it and had never seen his former aide since.

''I've found him!　How lucky we are to find them so quickly, when we were going to track them down to the ends of the earth and kill them!　After all, I am a demon who should be a hero, loved by fate!
Bashbursa!　Don't make this harder than it already is.　Ughhhh?!

　Glamberza, who tried to seize his son, was played back by a giant fist on the contrary.
　The huge fist that punched through the wall inside the demon king's castle and rushed in.
　It grabs Bashbarza and pulls him back as it is.

''Oops!''

　Bashbursa went outside with both giant fists.
　You're going to be able to find out what's going on.

"Flame Monster Beast Salamandra!

　The flaming dragon floating in the sky is a magical beast that is the same as the one that attacked the Mithril mine.
　Bashvaza stood atop its body.

''Good day, father!　I'd really like to kill you right now, but I'll do it later!　You know what I mean!　And as soon as Salamandra shares my spirit, she's going to be the first person I want to kill!
"You don't think...?

　Glamburza, roars from the wall.

'Yes, it's Dariel!　Dariel to kill first!　I will crush your eyes, pull out your tongue, cut off your nose, then slash off your limbs and give you the torment of hell before burning you to ashes!

　Bashbarza, who was using the demonic beast as an emissary, was conversely being driven by the demonic beast's rabidness by mental erosion.
　A mass of hatred loomed over Dariel, without knowing which one was being controlled by which one.