webnovel

Reincarnated in Mushoku Tensei: Realistically Overpowered (fanfic)

A reader reincarnates in the world of Mushoku Tensei as Seraphim Greyrat, the first son of Paul and Zenith born instead of Rudeus. Using his meta knowledge to the fullest, he aims to become the strongest existence of that world, using both sword and magic. ... Warning: A SLOW PACE FANF-FIC WITH A LARGE FOCUS ON MAGIC STUDY AND WITH A HIGH LEVEL OF DETAIL. STARTS OFF SIMILAR TO CANON. Seraphim studies the magic system of the world and Battle Aura techniques in depth to understand them fully and gain the best possible advantages. He becomes overpowered without external cheats, a result of his hard work and brains. Note: How this fanfiction is different from others in that many Mushoku Tensei fanfics seem to often get the magic system of the world wrong. The abilities that the Protagonists develop often go against the magic system of the world, are illogical and ridiculous, and something like this in my opinion completely breaks immersion. For example, ridiculous new magic spells and OP sword moves that get invented by an infant MC despite the fact that they are completely devoid of logic and are just impossible without cheats. Here, my Protagonist faces various obstacles and problems during training, that he should, while also gaining insights and does what is realistically possible to take his training and fighting methods to another level. He also achieves things that seem nearly impossible or fantastical, but with good logic and reason behind them. -It is a harem story, but I aim for meaningful romance and deep relationships. It is a harem story. However, harem is not the major focus of the story at all. It only means that the MC will have more than one partner EVENTUALLY. -Because the Protagonist accomplishes A LOT during his early years, there might be no real romance or even harem content anyway for something like 100 chapters. There will be no child sex here as well. There might be some romancing and teasing, but just that, nothing sexual. How this story is different from the original is that it is not about an MC searching for a cure for his ED, being passive and pathetic pervert all throughout the story while screwing around and doing nothing most of the time, but is a man on a mission. Seraphim starts from a similar point as Rudeus, but his actions cause a slowly spreading butterfly effect as he's focused on the most optimal path and BENEFITS. In contrast to Rudeus's perversion, the MC can sometimes instead be amoral and do evil pragmatic things for the sake of his ambitions and loved ones, so people with fragile hearts be warned. He is not as disgusting, but it doesn't mean he's a goody-two-shoe white knight. ... SUMMARY: -MC is born instead of Rudeus with just his meta knowledge and high talent. Taking more after Zenith, he has blonde hair and blue eyes. He trains his mana from an extremely young age, masters Battle Aura and chantless healing magic | A genius of magic and the sword, a determined true main character pursuing supremacy and eternal life. -The story will have a deep dive into the magic system and how the MC interprets it (how I interpret what we know using logic). It might be boring for some people, but it can be very interesting for others (would be for me). -The story starts with the same layout, and has slowly spread out changes as the MC is focused on BENEFITS. -The world is the same as in the original, the only AU change is the MC's body, looks and name.

Jaed21 · Anime & Comics
Not enough ratings
46 Chs

Chapter 36. The laws of magic, Conservation of Energy

Before entering the second floor, I visited the guild's store with Ghislaine and Eris following me.

"Excuse me, I want to buy a Magic Tool wand that shoots out Stone Cannon," I approached the male sales clerk and told him this.

I browsed the store before, so I already knew that they actually sell many kinds of items like this - Magic Tools that shoot out magic automatically when you input mana into it.

At the Elementary rank, Fireball and Water Ball wands seem to be the most numerous, probably because of their utility.

What slightly surprised me was the fact that there was also a quite good number of these wands in Roa's Magicians' Guild's store that shoot out Intermediate rank magic as well.

When going up to the Intermediate rank, there's less Fire and Water magic wands, and more Earth and Wind magic. I think it's because Fire and Water magic is not very suitable to use inside Labyrinths.

Either way, this kind of wand is something that should have worked as a base for Rudeus's gattling gun in the original story. I wanted to get my hands on one and test its effects.

"Because it's an Intermediate rank one, it will be one Asuran gold coin," the clerk said with a smile, then continued:

"In general, a Magic Tool wand like this is something that every magician should have. Although the magic consumption is slightly increased compared to casting Incantations with a normal wand, this tool can shoot out magic instantly, so it's a life saver!"

"A wand with the Stone Cannon spell is a great item to have to use in particular in an emergency against a single opponent, when an enemy gets too close or in a one versus one scenario. It's also the most mana efficient spell. It costs very little mana even when used without a staff! Against swordsmen below Advanced rank, and against most monsters, it's very deadly! The bullet that it shoots out is even faster than a typical arrow, and the casting time is less than half a second!"

The clerk hyped up his product with a smile.

I didn't need convincing though.

"Yes, I want to buy one."

The clerk smiled again and continued, "Good choice! Are you interested in a wand with a fixed aim or one that you can adjust?"

"What's the difference?"

This is actually one thing that I had no idea about. The wands on display were separated into these two types.

The man said, "A wand with an adjustable aim allows the user to visualize their target, but the one with fixed aim simply shoots the spell straight ahead where the tip of the wand is aimed."

"...And what's the difference? Why would someone want a wand without adjustable aim? Is it about the price?" I asked again.

"No, the price is the same. The difference is that the one with a fixed aim can even be used by someone who can't control his magic, but for the other one it requires a skill to control mana."

"...But shouldn't everyone be able to use Magic Tools, as long as they have mana?"

"Yes, that's true. When you input mana into a Magic Tool, the magic formation within casts the magic for you. However, aiming is another matter."

"I think I get it. Non-magicians can use Magic Tools to cast magic, but they cannot aim the spells with their mind because they didn't practice doing that before. That's about it, right?"

"Yes! Young master is very bright, just like the Guild Master had said!"

So Pascal had already told the clerk to treat me well, that's why his attitude is like that…

Anyway.

I got what he was talking about.

'Direction' is one of the variables that can be put into a Magic Circle, affecting the aim of the magic spell after it is cast through the Magic Circle, but it does not have to be included.

If the 'direction' is not included, then the person activating the Magic Circle will have to adjust it manually.

It's handy, because then you can freely aim the magic spell where you want it to hit.

Normally a magicians' spell simply flies toward where they want it to, toward where they visualize they want it to hit. It's extremely convenient.

Of course, once the spell leaves the caster's hands, it travels in a more or less straight line, so the target is still able to dodge it and the spell would not adjust its course.

However, aiming magic seems to require the ability to control mana that non-magic users simply would not have.

Hence, these kinds of people would opt for a magic wand with a fixed aim that works more like a real gun.*

I said, "I see. I want a wand with adjustable aim."

"Very well!"

The clerk hurried off to a side room and after a moment brought back the wand I wanted.

The 'wand' was actually just a 50-60 cm long round wooden stick with a hollow inside like a thin bamboo. 

It was difficult to guess whether it was a Magic Tool or just a stick, because it nearly looked just like a bamboo stick. The decorations were minimal and only allowed you to differentiate where is the beginning of the wand and where is the tip that shoots out magic.

"It looks like a stick!" Eris noted it as well as she got up closer to take a look at the thing.

"Haha! Yes, it does indeed look like a stick, young miss. You might think of it as a concealed weapon," the clerk replied with a forced smile.

'Not bad marketing skills,' I thought

Too bad that in contrast the person who actually made 'that stick' had no sense of aesthetics and marketing themselves. If he only made it a little cooler-looking, its price and demand on it could skyrocket.

Either way, I said, "I'll take it."

"Very well. Anything else?" 

"Yes, I'm interested in a staff."

"Oh!!! Are you going to buy a staff?" Eris suddenly reacted after being quiet for the most part.

"I just want to test it."

Actually, I had a hidden motive in testing the staff, actually.

It wasn't for myself.

It was for Eris.

I didn't plan to buy her one, but I wanted to test something.

Eris already managed to cast her first Elementary magic. My question is - could a specialized staff be useful to help her grasp silent casting of her Fireball?

If so, I'd just convince Sauros to buy her one.

"Young master, what kind of staff are you interested in? We have great staves for each of the four attack schools!"

"I'm interested in a Fire staff. The best one you have."

"Alright. If it's the best staff for Fire magic, then it's this one on display!"

The clerk approached one of the staff and began praising its specs.

A high quality wood compatible with fire magic and a B-rank Magic Stone on top from a Fire magic using lizard.

Apparently, it offered 4 times amplification for Fire magic.

That was the gist of it.

The staff was way too long for a 5 year old to use, as it was nearly twice my height, but the clerk didn't seem to care about it. I guess he cared more about a chance to sell the most expensive staff.

"Can I hold it?"

"Go ahead. Just keep in mind that it's forbidden to use magic inside the store."

The clerk gave me the staff with a smile.

I received it with both hands, then ignored his previous words completely and muttered, "Fireball."

As I sent my mana into the staff, a large fireball the size of a soccer ball formed at the end of it, high above my head.

"You… You…!" The clerk looked at me with a stupified and panicked expression and muttered.

I ignored him.

I knew about the rules of the store, but so what? How can I test the staff without testing it?

With Ghislaine and Pascal standing behind me, I could do anything I wanted as long as I didn't cause any actual damage.

It isn't that rules exist to be broken, but once you know the rules, you can come up with ways on how you can use them to your advantage.

I was timid in my first life and stuck to rules to be a 'good boy'. I won't make the same mistake again.

The clerk panicked and stuttered at my actions.

Rather than me being able to cast the spell so quickly with a shortened chant, he was probably afraid that there would be no way to dispel it and it would shoot off somewhere inside the store.

"It's fine. I can control my magic," I told him, then focused back on the staff.

While the clerk was opening and closing his mouth like a goldfish, I focused on the connection I had with the fireball for a while.

Then I dispelled the fireball and cast another one.

With just a bit of mana that would be needed for a fireball with the size of 1, the resulting fireball had an intensity increased a few times.

'It's as I thought, hmm… Is it?'

"Is it good?" Eris asked me.

I faintly glanced at her, then ignored her.

'It's as I thought. But I need to test it again.'

I continued playing with the staff, casting the Elementary rank Fireball a few times, as well as a Water Ball and a Wind magic spell.

By then, the clerk had calmed down a lot and only watched with a forced smile whilst Ghislaine moved in between me and the bodyguard in the room, standing there imposingly and expresionlessly with her hand on the pommel of her sword in a cool posture.

'Yes, that's right. My suspicion was right.'

After a while I thought I understood a little bit more about the nature of this staff.

In the past I have already tested using Roxy's staff on Water magic and on other spells.

Her staff did make my Water magic stronger with less mana, as if by drawing in more mana from somewhere into my spells, but the maximum power level of the magic I could use was still limited by my ability of 'mana compression', as I like to call it.

The important part was that there was a very unique feeling to it when you cast Water magic using Roxy's staff. It was as if it was made for using Water magic.

However, it was only about creating water. That feeling wasn't there when you tried to freeze something or when you tried to send water projectiles flying.

It still didn't allow for the user's Water magic to be noticeably powerful, but gathering the mana into a water spell came more 'easily' and more 'naturally'.

Now that I used the Fire-attributed staff which was on a grade similar to Roxy's staff, there was a similar feeling there when casting Fire Magic.

I can somewhat guess how a staff works.

Basically, while Roxy's staff made transforming mana into water easier, this staff made transforming mana into heat easier.

Or rather, I should say transforming mana into thermal energy, probably.

Roxy had already said this before - mana has no attribute by nature. When a magician casts magic, he transforms mana into another kind of energy or into matter.

Even people of this world, although often wrong about magic, seem to get this right.

"Seraphim?" Eris asked me again, but I ignored her as I was focused on my train of thought.

"Energy conversion. Energy conservation…" I muttered to myself.

In this world magic should follow the Law of Conservation of Energy!

In physics it is theoretically possible to transform any object with mass into energy and vice versa, which is a part of this law.

It is only possible in the most extreme conditions in my old world, but it seemed to be the norm in this world when it came to magic!

In other words, when using magic, a magician converts magical energy into thermal energy when using Fire magic, converts magical energy into matter when using Water or Earth magic, and converts magical energy into kinetic energy to send the spells flying and also converts magical energy into gravitational force to bend space-time and keep a spell afloat before release.

Looking at this law from another angle, it also means that each magical phenomena requires an equal amount of magical energy, like the Mana Calamity in the novel.

The Mana Disaster should have gathered the magical energy in the area and transformed it, using it to fuel Nanahoshi's summoning.

That's why all of the buildings, trees and objects at the affected area were not teleported, but all disappeared completely. They were converted into energy!

I originally thought that perhaps the buildings were sent somewhere to some other dimension just like Old Rudeus's internal organs, for example the Void World, but I was probably mistaken. What I just came up with made more sense.

On the other hand, humans, who inherently have a mana protection, were instead randomly teleported during the Mana Disaster, since Summoning magic and Teleportation magic are connected…

It was a quite mind-blowing discovery.

'I think Nanahoshi might have mentioned something similar. But it was so obscure and unimportant that I completely forgot about it. I had to reinvent the wheel myself.'

As the law of Conservation of Energy states: energy cannot be created or destroyed, it can only be transformed.

The total amount of energy in this world is always the same.

Mana is the universal energy source that can be easily converted into anything else. The possibilities of magic are endless. For example, it's theoretically possible to create a spell which converts mana into pure gold just the same as magic can make rocks and water.

Magic has these clear laws and nature.

What implications did my realization have on the current me?

Eh, I didn't know yet.

Even if I knew all this, there was only so much I could do.

But I felt that I at least had understood the principles of magic a bit better.

Instead of relying on what Roxy had told me, I had a more concrete proof of how mana and magic works…

But for the matter at hand, a fire-attributed staff seems to help with converting magical energy into thermal energy.

To help someone in grasping their first silent spellcasting… I don't think it would be useful.

That's because grasping silent magic is about imitating the feeling that comes from casting a spell and triggering the same pattern inside the body.

Converting mana into heat is more of the final step on the outside when the specific mana flow was already invoked.

In conclusion, an expensive staff with a fire-attributed Magic Stone will probably not help Eris in grasping silent Fire magic.

After giving back the staff to the sales clerk, I took out my guild card and money and paid for the Magic Tool wand.

With a 20% discount, I paid 8 Silver coins.

The currency in the Asura kingdom is like this:

1 Asura Gold coin = 10 Asura Silver coins = 100 Asura Large Copper coins = 1,000 Asura Copper coins.

For a rough estimate, if 1 Copper coin could be seen as something like 1 dollar, 1 Large Copper coin would be 10 dollars, 1 Silver coin 100 dollars and 1 Gold coin 1,000 dollars.

But in fact the value of a single gold coin in this world looks to be much larger than a mere 1,000 dollars on the modern Earth.

It had to do with income relative to a person's status.

For commoners, a monthly income would be only around 2 silver coins, the same as a typical person's monthly expenditure to live in a city unless they owned a house.

These are some rough numbers Roxy told me, at least.

As we left the store, Ghislaine curiously asked me, "Seraphim, why did you buy that Magic Tool? Can't you already cast your magic… You know…"

She meant silently. Yeah, I got it.

"Yes, I know. But I still want to test it. It seems it could be very useful if modified."

"Is that so?... Now that I recall it, our thief tried using one of those to have an option for ranged attacks. He was terrible at aiming with it though."

"I see."

A thief? I guess she meant Gisu...

Having bought the Stone Cannon wand, I went up to the second floor with Eris and Ghislaine.

Whilst Eris was excitedly registering herself in the guild, I browsed the request board.

That day there were new quests there, but again not something that I felt particularly interested in taking up that would promise quick money.

"Seraphim, look! I'm now also a magician!" Eris showed me her guild card after receiving one from Camille.

I gently smiled. "Congratulations."

"It's because Seraphim is a good teacher!"

I lightly chuckled. I didn't teach her all that much yet apart from the Fireball incantation.

After taking a walk through the city and visiting the food market in the adventurer's district, we returned to the manor.

While Eris began to spar with Ghislaine as the evening approached, I wanted to test the 'wand' I bought.

For the testing rig, I made an ice sculpture with a moderate hardness and a U-shaped stone wall behind it with gradually increasing layers of hardness. That should minimize the chance that the stone bullet bounces back at me or breaks a window.

Aiming the wand at the ice sculpture, I said the trigger word, "Fire!"

Mana was drained from my hand and used to rapidly form a stone bullet of a generic round shape of the [Stone Cannon] spell.

It took a near instant and the stone bullet was ready to be fired.

Using a basic amount of power, I fired off the bullet.

The result was an average level of power you'd probably expect from an Intermediate rank.

Of course, it didn't impress me at all.

After that I poured some mana into the wand again and a second bullet formed.

I tried to adjust the bullet's shape…

'As I thought, it's impossible.'

The bullet's shape, hardness and speed were all pre-set by the Magic Tool's magic circle.

The only aspect that could be adjusted was the aim - where the bullet would fly.

It made it so that the spell can be prepared and released in an instant with very minimal mental effort, but as a result its power was fixed and lacking.

I fired off the bullet I had prepared just to get rid of it.

After that I began to rapidly fire off bullets from the wand one after another.

Bam, bam, bam!

The round bullets hit the stone wall in rapid succession.

The speed at which I could fire off my spell was quite staggering.

What was that firing speed? About 5 bullets per second?

Quite nice.

An Intermediate rank swordsman or a low-mid grade monster would probably be full of holes from that in a second. Because it was an Intermediate ranked spell, it's also quite possible that it would get through steel armor and typical defenses of most monsters rather easily.

You could fire off the first bullet near-instantaneously against any sudden threat, then keep raining bullets at the target.

The wand was quite damn useful, being a user-friendly weapon.

But of course, it would be even more useful if the power was cranked up a notch. Perhaps I could convince Pascal or someone in the Magicians' Guild to do it.