After all, the Demon King-sama stayed in my mansion for a long time.

　The leave I gave my men was three months, and she must have stayed in my mansion for most of that time.

　During that time, the Demon King and I enjoyed our encounters - or not, we just spent time for no reason.

　From time to time, he would play chess with me, learn to knit with Sati, or tend to the rose garden in the mansion's garden.

　Of course, I wasn't spending all that time idly.
　The design of Azuchi Castle is basically done by Cephiro.
　She was the most eccentric of the Demon King's army, but she was also the best engineer in the Demon King's army.
　I'm sure she was a master at building castles.

　What kind of castle is she going to build when she comes to my mansion?　He asked me a question.

'The Demon King is there and you're going to do it to me?

　I ask him this, but Cephiro replies, "The Demon King says that he has left everything to Ike.

"The Demon King says he's going to leave everything to Ike. As a vassal, I have no choice but to obey him.

　Cephiro said, and let out a breath to the Demon Lord who was knitting with Sati.

''I can't let the other executives see this scene. It hurts the Demon King-sama's authority.''

You know, just from the sight of him, he looks like a girl about Satie's age.

　I replied and told her about my plan for the new Demon King's Castle.

''As for the new Demon King's Castle, I think the Demon King's plan is to have a castle that is gorgeous and simple.''

It's an abstraction. Could you please be more specific?

''I'm sure the Demon King's intention is to make the land of Azuchih the economic center of this continent. Therefore, I want to increase its scale.

'Hmm. But if it's too big, it'll take too long to build.

Let's sacrifice some of our defenses for that.

Isn't the castle and the defenses a two-in-one set?

　Cephiro exclaims in amazement, but I explain.

''That's true, but to put it another way, defense and development are a trade-off. If you build a solid fortress from the start, there's no way to expand it any further.

That's true, but...

I want to make Azuchi the hub of this continent, a city of one million, or even three million. So instead of surrounding the city with walls, I want to fortify only the castle part of the city so that it can be expanded later.

So that's how it works. I think it's called a sogamae, or so-called a sokurawa.

That's right.

　I affirm that.

　In this medieval-like alternate world, fortified cities are the norm, but it would be better to build a castle in the center of the city and enclose the city with a simple defensive wall for its development.

　In Japan, the famous Odawara Castle is probably the most famous castle in the world.

To begin with, the land of Azuchi is surrounded by rivers and is a natural hazard. That alone would be enough to deter an invasion by the enemy.

So, I've found some good terrain.

It's because the Demon Lord made you happy.

But it won't be a match for the defenses of Dvorberg, the home of the Demon King's army.

That castle is very special.

　The Demon King's Castle Dvorberg is designed as the last stronghold of the Demon King's army.
　It is built on top of a precipitous cliff, making it nearly impossible to attack that castle.
　In fact, it had been attacked by humans many times, but each time they had managed to fend off the enemy.

''But this time, we don't need a castle as defensive as Dvorberg's. What the Demon King's army needs is an offensive castle.

A castle to attack?

　Sephiro raises his eyebrows snidely.

''As I've said many times, I want Azuchi's castle to be a base for the Demon King's army as well as an economic center. Besides, I don't like the idea of a robust castle in the first place.

'That's a problematic statement for the planners of the castle builders, I suppose.

Well, the only time I can say this is in front of the Commander.

　After saying so, he laid out his thoughts to her.

''To begin with, I believe that the term impregnable castle is itself a trap to make soldiers proud--''

　In fact, every fortress that had been called impregnable, including those of his previous life, had fallen.

　Odawara Castle, which had avoided 100,000 troops led by Uesugi Kenshin and tens of thousands of others led by Takeda Shingen, fell helplessly in front of Toyotomi Hideyoshi. It was made to surrender without fighting.

　Osaka Castle, which was built by Toyotomi Hideyoshi, was also brought down by Tokugawa Ieyasu.
　Not only in Japan.

　Contatynople, the capital of the Byzantine Empire, the capitals of the Chinese dynasty, all thought that the owners of their castles were impregnable, but more than once they fell to their enemies.

　That's history.
　Why is that?
　Because impregnable is the key point where the enemy has to strike down.
　The land of Azuchi is a key point in this world.
　The enemy would surely send an army to overthrow this land.

　Of course, you need to have the defensive strength to drive them away each time, but the effort to prevent the enemy from attacking you is even more necessary.

　It was at the end of the day, when they were cornered, that they would fight by hiding in their own grounds.
　He didn't want to build a castle with such an expectation in mind.
　When I explained that to him, Cephiro nodded his head in agreement.
　I spit out the most appropriate words for the occasion.

'A man is a castle, a man is a stone wall, a man is a moat, mercy is a friend and revenge is an enemy.

Well, it's a word I've never heard before.

　Sephiro is interested and asks what the words mean.

'No matter how strong a castle you build, if you lose a man's heart, it will fall in a flash. That's what they say.

I see.

I'd rather think about the people who live underneath the castle, than having it so tightly fortified like Dvorberg. There should be many different tribes from all over the world coming together to create a city for them to live in.

Hmm, I think so, mistress.

　As she said that, she seems to have decided to keep the construction cost of the residence part of the Demon King's Castle to a minimum. However, she still seems to have pride as an engineer and wants to build a castle that is more robust than the royal capital, Liesus.

　He recommends building more stone walls and moats around the castle walls.

　It's a construction method not often seen in this other world. She further complicates the interior of the castle by offering to build turrets and wall holes to unilaterally attack invading enemy forces with guns.

　I agree with that.
　This is the same idea as in Japan's castle building.
　It's a suitable structure for the Demon King's castle. I thought so.
　Once I got an agreement with Sephiro, I left the building of the castle to her.
　I thought there would be no problem in leaving the design to this witch.

　The other important part of the construction is that Günther, the dwarf king, will take care of that. It's a pity that he's the only one who can't take a leave of absence, but Günther doesn't seem bothered by it at all.

'Of what. You will be able to take part in building a castle that will be remembered in history. It would be shame for a dwarf to rest here.

　He worked hard to say so.
　His words were most gratifying.

　When the basic design of the castle was completed, Cephiro went back to Riesas and began to draw up the plans. Günther began to build the castle according to the plans.

　Building a castle takes time.

　Even in his previous life, it took seven years to build the famous Kumamoto Castle and 15 years to build Osaka Castle. Of course, it took a long time to build the castle town and all the other details.

　However, Azuchi Castle was intended to be completed more quickly than that.

　I heard that the historical Azuchi Castle took three years to build, so I wanted to finish it in one year, a third of that time.

　In order to make this happen, I called Luthrara, the person in charge of building the castle, to Ivalice.