Goshujin-sama to Yuku Isekai Survival! – Chapter 157

It’s Ko-Fi’s Supporters’ chapter (92/115), enjoy~

Chapter 157 – Prototype Air Bike


They say that failure is the basis of success.

When we fail, we should reflect on the cause of the failure and improve our methods and shortcomings, which will lead to our ultimate success or something like that. In other words, what is the point? You know what I mean, right?

“Ugh… ueekk.”

“Fight, Kosuke.”

“I-I’ve got this… orororo.”

“That’s dirty, Kosuke.”

I feel like I’ve been having a bad relationship with vehicles lately… No, this may be a normal part of vehicle development.

In conclusion, by attaching the levitation tool to the square of the board, we were able to avoid the board from leaning too much. However, we cannot put the golem eye that measures the height on the square and keep correcting it to maintain a certain distance from the ground.

If it’s moving on a flat surface like a paved road, there’s no problem, but if it’s moving in the wilderness, it’s shaking like a ship in a storm. I felt sluggish within five minutes.

Undeterred by our failure, Isla and I continued to make improvements. How about reducing the frequency of correction by the golem eye? How about using four sensor locations, front, back, left, and right, instead of a square? Wouldn’t it be better to have a single sensor in the center? In other words, don’t we need a sensor? It took me too long to realize that.

That’s right; there was no need for the sensor correction in the first place.

This levitation magic was designed to maintain the height according to the amount of magic power based on the location where it was first activated, no matter how much it moved. The magic itself contained a formula to memorize the reference point of altitude. There was no need to go to the trouble of installing sensors in the square, updating the altitude reference point in real-time, and correcting the tilt.

In other words, we set up the levitation tool in a square to keep the balance of the object we wanted to levitate and placed the sensor in the lower center of the vehicle to measure the reference point when it is first activated. The sensor that measures the reference point when it is first activated is placed at the bottom center of the vehicle. All that was needed was a mechanism to equalize and control the amount of magic power flowing into the magic tool.

It was a roundabout way to go and a painful waste of time and effort.

“I’m sorry… I haven’t used levitation much.”

“No… it’s good that it turned out to be a success. You were able to reconfirm the magic principle of levitation. But I wonder what would happen if we used it on top of a high mountain or something?”

“I don’t know…? I have never done it before.”

If you use levitation on top of a high mountain and move towards the bottom, will you be able to maintain the altitude….? If the point where you used levitation is the reference point, then theoretically, you’d have to try… to find out. I have a feeling it won’t work that way.

“Anyway, now we have a cargo bed that doesn’t shake and isn’t affected by the ground. It can be used as a tool to carry heavy things, right?”

“Hmm, even a child can carry a carriage full of heavy things with this.”

In fact, we put heavy objects on this experimental device, which was the size of a seat cushion, and even Isla was able to move the objects with ease. However, the larger the load, the more magic power it consumes, so if the magic power suddenly runs out while transporting a heavy object, a major accident could occur. Some kind of safety device would have to be installed.

“Next is the propulsion system. I have a plan for this. I just need Isla’s cooperation.”

“Of course, I’ll cooperate.”

“Yes, thank you. As a court mage, Isla’s cooperation is essential. You know wind magic, right?”


“Well, there’s wind magic that just makes the wind blow, right?”

“Yes. That’s the simplest kind of wind magic.”

When Isla pointed her fingertips at me, a light breeze blew into my face from her fingertips.

“Yes, that’s it. I wonder how it’s generated?”


Isla tilted her head at my words.

“No, wind is the flow of air, right? It’s not like the air is coming from your fingertips; it’s probably gathering air from around you and releasing it through your fingertips. Can you keep blowing air out of your fingertips for a minute?”

“Hmm, okay.”

After a lot of experimentation, I found out that wind magic is indeed gathering magic from the surrounding area and spewing it out of fingertips or the tip of a wand.

“I have learned the truth… that I thought I knew, but I actually know nothing about magic.”

“Well, I suppose it doesn’t really matter when it comes to the normal use of magic, does it? But, hmm.”

I learned that some wind magic gathers the surrounding air and releases it in a certain direction. Eh? You didn’t understand the magic? The magic of shooting invisible wind blades and compressed air bullets is beyond my knowledge… What kind of principle is that? I don’t know anything about it.

Anyway, what I have tested this time is a magic that shoots wind from the fingertips or the wand’s tip. This is a magic that gathers air from the surroundings and releases it in a certain direction. In principle, it is the same as a jet engine. However, there is a clear difference between it and a jet engine.

“I knew something was wrong.”

“What’s wrong?”

“No, it’s like a strong wind spell, where the wind blows so hard it blows you away.”

“Hmm. With the higher wind pressure magic, you could literally be blown away.”

“Yeah. It’s not just that… it was dangerous. So, if you’re using magic that can blow up an entire person, why isn’t Isla being blown up?”


Since the jet is formed by taking in air from the surroundings, there must be a reaction to it. If you think about the law of action and reaction, it is logical that you should also be blown away by the air jet. I have already confirmed that the third law of motion is functioning normally in this world. So, I explained the law of action-reaction to Isla and explained that it doesn’t make sense for her not to be blown up.

“…Is it because it’s magic?”

“Don’t give up! You shouldn’t give up there! Why are you giving up right there?”

“That’s not what I’m saying.”

If you’re convinced that this is the way it is, that’s the end of the story. No, there is a way to get propulsion even as it is now, though, right? If you set up a sail on a levitation board (which I just named) and blow wind on it with wind magic, you can complete a ship that runs on land. But by figuring out the wonders of this wind magic, we should be able to create a faster, more efficient propulsion system.

“In other words, there must be some kind of recoil-canceling formula built into the wind magic. You see, even the Harpies and dragons like Grande fly with wind magic, right? But if you think about it with the common sense of normal wind magic, it’s strange, right? That way.”

“Hmm, that’s strange. The magic efficiency is obviously… something like that?”

“Have you noticed anything?

In other words, that’s what I’m trying to say. This is probably the secret of the flying method used by the races that use magic power to fly, like the Harpies and Grande. They are able to fly for a long time with surprisingly little magic power consumption. It’s obvious that they use magic to fly, and we know that it’s wind magic.

But from the common sense of magic, it’s strange that these girls can fly. If they were to maintain the power output of wind magic to keep their bodies afloat, they would consume too much magic power and would not be able to fly for such a long time. As for the dragon, they are huge. No matter how much more magic power a dragon possesses than a human being, can they continue to fly at ease? That’s the question.

“…Are you okay?”

“…It was more impressive than I imagined.”

After contemplating something for a while, Isla said that she would try to shoot advanced strong wind magic, so I set up a fluffy straw block behind her and let her try out the new magic while I supported her from behind.

As a result, Isla and I both flew backward and crashed into the straw block.

“It’s fun to learn new things when I’m with Kosuke.”

“I don’t feel bad when you say so, but please be careful. This time, I knew that the reaction would probably blow you away, so I was able to take precautions beforehand. Don’t mess around with other magic to activate it and cause a major accident, okay?”

“Hmm, I know. I’m still a long way from exploring the truth, but I’m still a former court mage. And I’m a lot older than Kosuke. No need to worry.”

Isla stretches her small breasts out with straw scraps on her head. Well, Isla is a thoughtful person… isn’t she? Sometimes in the heat of the moment, she can’t see what’s going on around her… I’m worried.

“In any case, we now have the propulsion system in place. As for the structure… a simple tube shape is fine at first.”

There may be a more suitable shape, but for the time being, a cylindrical shape will do.

“Can I use wind magic, minus the recoil-removal technique, inside this tube?”

“Yes. That’s fine. Is it possible to reverse the direction of the jet?”

If you can reverse the direction of the jet, you might be able to use it as a brake. Let’s see what we can do about the brake problem. First of all, it has to physically touch the ground… Or, is it possible to use air resistance to make an air brake? No, it’s not a mechanism, but how do you get that much air resistance? The first thing to do is to use a normal ground brake.

“It’s possible. I’ll make it so that the power output can be adjusted, just like the levitation magic tool.”

“Maybe we can make the output adjustable on both sides. I think we can turn with the difference in power.”

“Hmm, okay.”

It would be better to add a directional rudder at the rear. It might be better if the power difference between left and right is linked to the directional control. This can be thrown to the research and development department.

While Isla was working on the magic tools for propulsion, I was working on the ground-based primitive braking mechanism and the body to hold them. The body of the vehicle is just a wooden board about the size of a seat cushion that has been replaced with a wooden board about the size of two tatami mats and a levitation magic tool attached to the square.

“It’s done.”

“Then let’s make the golem core for output adjustment and the control mechanism.”

I don’t intend to make the control mechanism too complicated. Should I name the wind magic tools… attached to the left and right levers on the left and right sides of the body? The official name should be Wind Magic Propulsion System. Just propulsion system is fine.

The left and right levers can be used to adjust the output of the left and right propulsion units. Tilt it forward to move forward; the more you tilt it, the more the power increases, and tilt it backward to move backward. When the left and right levers are tilted outward, the plane rises, and when they are tilted inward, the plane descends. By descending, the plane touches the ground and also acts as a brake.

“…It’s a little awkward.”

“It’s a prototype, so it can’t be helped.”

The design of the prototype is similar to that of a certain blue cat-shaped robot time machine, and this was not an accident. If it is to travel at high speed, it will need a windshield to protect the pilot from wind and flying objects, and the design will be refined. It’s just an experimental device, you know. [T/n: Doraemon time machine.]

“All right, let’s get this thing running.”

“Be careful.”

“I got it.”

As long as it doesn’t kill me instantly, I’ll be fine. I seem to have become surprisingly strong since I came here.

The first step is to press the activation switch to start supplying magic power to each of the magic tools. The next step is to push the left and right levers outward to raise the aircraft off the ground.

“That’s it for now.”

“Hmm, it’s floating.”

“Let’s try the vertical movement first.”

I pushed the left and right levers inward and outward to raise and lower the prototype levitation device. There seemed to be no problem.

“Okay, no problem. Now let’s start testing the wind magic propulsion system.”


The experiment on its own has already been a success. The first one was blown far away because the propulsion was too strong. I decided not to go looking for it because it was too much trouble. Since I flew towards the Black Forest, at least there is no chance of any secrets leaking out to the people of the Holy Kingdom… Yes, I apologize for being so careless.

Aside from that, move the left and right levers forward. The output can be adjusted in four stages depending on the angle at which the levers are turned down.

“Oh, good, good, good.”

“It’s working fine.”

At the lowest power, the vehicle moves through the wilderness with a swoosh. It seems that at the lowest power, the speed is about the same as a person walking. It can also turn by varying the power of its left and right propulsion units.

“Okay, let’s try to get some speed.”

“Hmm, be careful.”

When I pushed both levers forward one more time, it became as fast as running. When turning, the inertia of the ship causes it to skid, and it takes some getting used to for precise control.

I raised the altitude of the prototype for high-speed navigation. I didn’t want to get hurt by hitting a rock or something.

“Whoa! Waee! Ouch!”

When I raised the altitude and put it into the highest gear, the fourth gear, it was faster than I expected. I think I was going at least 50km/h. The wind on my face was strong, and more importantly, the dust from the wilderness hitting my face hurt. After all, the vehicle itself needs wind protection or goggles, masks, or full-face helmets for the passengers.

After realizing this, I slowed down and returned to Isla’s place.

“I’ll ride next.”

“That’s good, but you’d better keep it to third gear. It’s hard with the wind blowing in your face and the dust hitting your face.”

“Don’t worry. I’ve got magic.”

“That’s one way to do it!”

There’s no need to install a windshield. The wind barrier magic will take care of it. Maybe I can build it into the body. I’ve never thought of using magic to prevent that.

Isla’s prototype levitation device ― that’s a long story too. I’ll just call it a prototype air bike. We get on the prototype air bike and ride out into the wilderness. Hmm, Isla is a careful driver. She’s not the type of person who changes her personality when she gets behind the wheel.

When Isla returned a few moments later, she looked very satisfied.

“This is a good one. When this is mass-produced, it will revolutionize travel in this world.”

“You have to be careful not to get into a traffic accident… It’s faster than a carriage, so it could lead to a serious accident.”

“That’s true. In addition, if they are captured by the Holy Kingdom, they may be imitated. The technology itself is just a product of this world.”

“That’s right… Well, I think it’s inevitable that this will happen if it becomes widely used.”

“Hmm. But this…”

“Prototype air bike.”

“Some of the technology used in the prototype air bike can be used for military purposes, and the prototype air bike itself can be easily converted to military use. We have to be careful.”


I wonder if a wind magic propulsion system or something like that could be incorporated into a spear to make it as powerful as a ballista without a launcher? Of course, the shape would have to be devised for speed and stability in flight.

If you combine it with gunpowder, explosives, or magic tools that contain explosive magic, you can create a powerful weapon. I’ve made anti-tank rockets myself, but when it comes to the propulsive power of the warhead, a wind magic propulsion system might be less expensive in terms of technology and materials if made with the technology of this world.

“Besides, the technique used to eliminate the recoil of wind magic… may also be dangerous if it is known.”


“I’m not sure yet. But, it might be possible to create a new magic.”

Then Isla pondered. Magic that erases recoil, huh…? I don’t know the principle, but it sure looks like it could be used for something.


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7 thoughts on “Goshujin-sama to Yuku Isekai Survival! – Chapter 157

  1. You can also apply this magic to a big battering ram made from hard stone and metal to punch holes through castle walls, field fortifications or lines of heavy infantry. Think of these wrecking balls swung by a lifting crane for reference.

    Liked by 1 person

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