I thought for a moment, not immediately swallowing the meaning of Arte's words.

　The Seven Demon Kings.
　They are the kings of the demon race and demon kings that lie deep within the ruins.

　It is said that Princess Filia is their descendant.

　The Demon Kings are said to be located in the seven ruins of the ancient kingdom era, and each one of them has one Demon King.
　That's why they are called the Seven Demon Kings.

　For example, the dead city of Necropolis is the very place that was the capital of the ancient kingdom, and it is said that the Demon King sits in the deepest part of the city.

　But I had my doubts about how far that was true.

　For another two thousand years, no one had seen the seven Demon Kings.
　The ancient kingdoms were said to have been destroyed by an invasion of demon kings.

　But that's the kind of legends and myths.
　Even if there was a time when the Demon King led the demon race and demons to destroy the human kingdom, it was long gone.

　Nowadays, demons are targets to be defeated living only in the ruins, and demons are persecuted by ordinary humans.
　I believe that even if there was once an existence called the Demon King, it has all but disappeared.

　However, there are beings called the descendants of the seven demon kings, that's for sure.
　Among the demons that have left their old blood, only a small percentage are descended from the Demon King.

　It is said that the Demon King used his inexhaustible magical power to continue attacking the cities of the ancient kingdom until they were completely destroyed.
　In other words, the Demon King had a large amount of magical power, and those who are said to be descended from the Demon King also boast an extremely high amount of magical power.

　That's the knowledge I got from a book, the descendants of the Demon King were extremely rare and I had never seen the real thing.

　Arte says.

''The Demon King's descendants resonate with high-ranking magicians like us. The descendants of high magic kings are attracted to the presence of superior sorcerers and can sense who they are dealing with.''

'I see. I certainly thought the boy had a pretty good aptitude for magic, but I guess that's about it.

''Senpai wouldn't have realized that the girl was a descendant of the Demon King. Because she's a less than fourth-rate magician.

'I'm sorry. But now that I've figured it out, is there anything I can do differently?

''Even you know what role the descendants of the Demon King have. You know what the descendants of the Demon King have to do. Because you only have the knowledge, don't you?

　Arte said mockingly and I nodded silently.
　The descendants of demon kings who boast a high amount of magical power have been used by humans throughout history.

　They have been used as a source of living magic power, in other words, as a tool for magicians.
　With great magical power, magic would be much easier to use.
　If the descendants of the Demon King were held back beside them as tools, human magicians could greatly enhance their magic.

　However, it comes at a great cost.

　The side of the Demon King's offspring would have to be "modified".
　Normally, the magic power that people and demons have is for their own use.

　Therefore, in order to make it possible to supply magic power to others, the 'output' method needs to be changed.
　The descendants of the Demon King who were thus altered would never be able to use magic by themselves again. On the contrary, it is not uncommon for them to become crippled due to the effects of the modification surgery.

　However, it's not a problem for the magician.
　They are just tools, so it doesn't matter what happens to the descendants of the Demon King.
　As long as the demons and half-breeds are slaves, there is no legal problem.

　Arte's eyes sparkled.

''That silver-haired kid has great qualities. I'm sure the blood of the Demon King is very thick. It's hard to find a descendant of the Demon King who has that much magical power.''

You seem to know a lot about this, Arte.

''Yes. Because after my seniors disappeared, I've already enslaved and 'used' three descendants of the Demon King's descendants. The first and second weren't very useful, but the third one was a pretty girl like that silver-haired girl and was a very useful tool.

What happened to those kids?

It's broken, isn't it? So I need a replacement.

　Naturally, said Arte, plainly, as a matter of course.

　I was horrified.
　Broken, which would mean dead or close to it.

　But Arte didn't seem to feel guilty at all.

''It's inconceivable to me that senpai isn't using that girl as a source of magic power. That's why senpai is fourth-rate.

He's my student. She's not a tool. If we modify her to supply magic, she won't be able to use magic.

''I feel sorry for her, being a senior's disciple. If he was taught by his seniors, he would end up a bad magician like them. Then I should be the one to lead her to a more suitable path.

A more suitable path?

'It means that you're going to be a tool of the female sage Arte, and you're going to have a glorious role in supplying her with that magical power. Because that's what makes her happy.

　I'm raptured.
　I have no idea why that's the way the conversation is going.

　The part about it not being good for Filia if she was being taught by me might have a point.
　But that said, why would being a tool for Arte's sake lead to Filia's happiness?

　To my question, Arte answered.

I'm sure you'll be happy when you use the power and talents you've been given, whether you're a human or a demon, to perform your duties correctly. That's what I think.

So, to that boy, being a descendant of the Demon King, being useful to a wise man is what makes him happy?

　When I asked back sarcastically, Arte nodded hesitantly.

'No one should need the daughter of a dirty blood demon. It's of no use to me. That's why I'm the one who needs her. I'm not just going to take the girl, I'm going to take her too. Isn't it the greatest honor for a dirty-blooded half-breed to be an important tool of the Empire's most powerful adventurer?

　Indeed, the Imperial Lady Filia may not have been needed by anyone in the Imperial Palace.
　Her father, the emperor, had ignored her existence, she had no mother, and the imperial palace guards and servants had kept Filia away from her.
　But now it was different.

'Arte. You are mistaken. The boy will be a great magician. And she is my protégé. I need him.

Yeah.

　Arte laughed with amusement.

''I'm looking forward to not only finding a replacement for the tool, but also taking away something important from my senior, in two ways. I can give that girl a 'modification' in front of her seniors. That thing looks like it hurts a lot, so it will make her cry out in a good voice. Oh, but I'm sure senior won't be able to talk to her then either.

'I can't do that. The girl is Filia, the Eighteenth Princess of the Empire. There's nothing we can do with her.

　I hung up my trump card.
　I didn't want to bring up the fact that Filia was an imperial princess as much as possible.

　Since it's known that she's the devil's daughter, it's even risky to bring up Filia's name.
　But in order to prevent Sophia from being brought back, and to protect Filia herself, using the authority of an imperial princess is the best way now.

　But Arte kicked my words to the curb.

''I at least know that she's Princess Filia. The fact that the senior has become the tutor of Princess Filia, and that she lives in this house with the princess, her maid and Sophia-sama, all of it. I've already investigated it.

So you're saying that you know and you're rebelling against the Crown Princess?

''It's fine as long as they don't find out. The imperial government doesn't desperately want to find out if there's a half-breed princess who is missing. Our knights have been given police powers by the Empire. It's easy to cover up a violation of the law.

　I looked at Rylen Remilia's face as she lay there, hurt.
　Her face is contorted with intense pain.

　Are Arte and the others planning to cover up the assault on Lailen Remilia as well?
　Even if they were to do so, they couldn't so easily pretend that the criminal act against Lailen Remilia, the daughter of a nobleman, wasn't there, and it would be even harder to cover up the kidnapping of the imperial daughter.

　It's hard to believe that Creon, the new Deputy Commander, would have agreed to such a foolish act.
　However, the wise man Arte seemed confident.

''Our new patron has a person and organization involved in the heart of state power. So you don't have to worry about your seniors. Rest assured.........get killed!

　As she said that, Arte pointed Yanagi's staff straight at me.

　Almost at the same time, Saint Sophia appeared on the spot.