Ryoma: "Time for unlimited throwing axes that can come back by themselves"
Treant: "But that's cheating!"

It's only cheating if you're the loser. Lol. Otherwise it's a sound tactic.

tree that can walk... yeah... i think the judges will allow endless axes vs walking trees... ;)

I was expecting Ryoma to dealt the finishing blow with big axe lol.

Five will get you ten that the demi-humans love Ryoma more than those catgirls love catnip, I'd bet. Now, who do I need to delete around here to get a Pyon to snuggle with?

how "ironic" plot it has

I believe slime can fly

I believe slime can touch the sky

Think about slime every night and day

Spread my slimes and fly away

I believe slimes can soar

I see slimes running through that open door

Ryoma Kelly?!

I believe I gonna be the very best that no slime ever was....

To catch slime is my real test, To train them is my cause

Sees the new slime
"He's going to built an airship isn't he?"

Flying confirmed.

maybe he starts with an elevator

A space elevator haha

weightless spell would affect folks inside the elevator too, you would be floating inside it as the elevator floated up. then, how would you go down? ropes and counterweights? why not just do it mechanically, then you wouldn't need a mage. magic machine item motors! spin shafts with ropes/chains/cables attached and you essentially have an 'electric elevator'.

An engineer i see. Good one man, but you forgot about the counter weights, breaks and anti slip/fall system in case of power loss.

☝️😲👍

The Fluff Slime looked interesting, it looked like it was going to be really small when it first appeared.

Seeing Ryouma use the slimes as projectiles was interesting too, I guess he could make them into a bow and arrow too and just have an infinite amount of arrows at his disposal.

well, considering the slimes have to physically come back; i don't think a bow's range would work as easily. each 'arrow slime' would have to get back to you pretty quickly to keep your quiver 'full'. if he trained metal and iron slimes to be fast enough... why not just use regular arrows instead? he does have a bottomless pit of storage space. just have a slime toss out a full quiver of regular arrows from storage to you.

now the BOW would be an interesting idea. a slime could adjust the shape, strength etc. of itself depending on which shot you were taking. a short-range light pull for small game near you, up to a grand bow longer than you are tall with a pull so hard you can barely get it to your cheek and launches an arrow at a target hundreds of yards away. plus the slime could adjust the tension of the limbs AFTER you pull the string back. basically, you easily ... like baby rattle ga ga goo goo easy... pull the string back and aim.... for the adjusted trajectory of course... then when you release the arrow nock the slime-bow turns into 'uber super ultra power man!' tension instantaneously and LAUNCHES the arrow faster than you could have physically placed tension on the limbs of the bow. :D

Long story short

Bow slime good

Arrow Slime bad

bingo! give this person one imaginary internet cookie! ( @ ) :D

Sounds nice, though you also have to concider you still need the armstrenght to endure the resulting counterforce. Though he could just have slimes make a ballista.
Also arrows would not work, the anime seems to ignore it, but they still have cores, which are a fixed size.
For instance the novel states that he puts them under the grip for his katana as the blade and grip are too thin to house the core.
As such arrows would not work as the core would get in the way, the best you could do is a bolt thick enough to hold the core inside, which would be quite big.

counterforce? what counterforce? speed inertia movement weight mass are all minimal with a bow. you would have minimal effort/kinetic/potential energy placed into the limbs and string if the slime bow started off 'weak' THEN changed as i postulated into a 'stronger' bow after you released the arrow. for example, Light wooden arrows weigh about 350-400 grains, medium-weight arrows are between 420-500 grains, heavy arrows weigh more than 600 grains. In pounds, light arrows weigh between 0.05-0.57 lbs, medium weights between 0.06-0.072 lbs, and heavy ones weigh more than 0.085 lbs. you're going to shoot that arrow at maybe... in a recurve up to 225 feet per second (fps) or 150mph, while arrows from a compound bow travel at up to 300 fps (200mph). now, i've shot firearms with bullets easily in the 300 grains range (Browning 50) as well as bullets in the .243" caliber that only get as heavy as 75-100 grains. but, those are launched from O to 2000+ fps. so recoil is present.

the movement of a bow is described two ways: as the possible/probable declination/deformation of the limbs from 'relaxed' to 'strung' to 'drawn', then the distance the string travels from your cheek to the 'strung' position at rest after the arrow is released (AKA draw length). a great deal of the kinetic energy of the string's motion forwards drives into and through the arrow propelling it beyond the string and towards the target. the remaining energy is dispersed throughout the string and limbs and grip of the bow. the left over kinetic energy from the limbs returning from drawn to relaxed strung is dispersed through the structures of the bow.

i've always equated a bow to be so similar to a pole-vaulter's pole. they gotta run and carry it, plant it, they keep running forwards as the pole flexes and they jump up and 'yeet!' are launched upwards in an arc to clear the target and get over it. but the bow does that with a string tied to each end of the 'pole' instead of the ground and person at each end. :D i do agree though, the shock and shuDDer in the bow's handle will be felt in your hand. as to the strength of that remaining kinetic energy as it moves through the bow... hmm... gooey slime CORE inside a hardened 'shell' of slime forming the bow. the force would be dissipated through the goo easier than a solid 'hardened' metal/iron slime from tip to tip of the bow's limbs.

ballistae! mhm excellent idea! much bigger projectiles. :D i've even seen concept blueprints drawn up by 'enthusiasts' utilizing pre-loaded 'magazines' filled with stacked crossbow/ballista bolts. but most of the 'enthusiasts' forgot the 'string' is pulled back over the 'body' of the siege weapon to cock-it. the string would catch/knock off a 'rising' projectile being pushed up by the follower of a spring-loaded magazine. my only idea would use a push button magazine 'notched catcher'. it would hold the follower down so the projectile is still inside the magazine and 'pops up' after the release trigger is clamped on the string.

aha, the core, the 'face looking' part that floats inside the slimes. i had forgotten about that part. thanks for the reminder! :D

Well science people here. Hello my fellow science user. Great comment and source of info. Its really good to have people who understand engineering and weaponry like ballista cause many people especially in the movies get them wrong especially the balista with magazines and some rapid fire ones.

"It can't rust pure iron"
Clearly the guy who wrote manga/anime has zero actual knowledge about pretty much anything tech/science related.

Same as with the ascendance of a bookworm, the author is clearly not a techie. A humanities scholar who maybe had read a pop-science book or two and even that is not a given. Trying to appear more knowledgeable than they are.

And since we're on the subject of BS statements in manga/anime, there was a line in
"the tale of outcasts" that made me facepalm. It went something like this:
[Demon]: "How is it possible for you to cut my hair"
[Knight]: "The katana is the sharpest sword in the world"

Katana isn't the sharpest or sturdiest or the best in any other way. This myth was debunked hundred times already.

It's not like he is claiming iron doesn't rust, hes simply saying the Elder Treant doesn't have the power to rust pure iron. Pure iron is a lot more resistant to rusting then your run of the mill iron is.

yeah i think you are right, either that or the author got confused between pure iron and stainless steel, still since it comes to magic probably the spell is just not strong enough for higher levels of rust resistance or something like that, I don't think is meant to be taken too deeply anyways

He can turn solid steel axes to dust in tenth of a second, but cant even begin to corrode "pure iron".

Also, you do realize that that was magic? Why would normal chemistry apply here? What if the spell takes the oxygen atoms and teleports them right next to iron atoms and forces them together? In that case purity does nothing.
It's just lazy writing. Ryoma makes a guess based on physics of our world and for some reason he is right! Again and again, time after time. Every guess he makes based on his knowledge of his original world turns out to be correct.

You seem to have missed the whole reasoning behind why he believed it would be fine. It was pretty subtle so it isn't much of a surprise that people would have missed it, but if you remember way back when he was testing different things with the slimes and gauging their reactions he came to the conclusion that they have a highly developed sense for danger. The metal slimes shook in fear because they knew what the elder treant was capable of and the danger it posed to them. The iron slimes however did not. It was that simple. It wasn't a guess, he trusted their sense of danger and his comment of it being because they are pure iron is simply him rationalizing why it didn't effect them. I am sorry that they didn't go into great detail to explain it all to satisfy your pessimism...but I have a feeling if they did that then this show would get so dull that no one would want to watch it anymore. But hey, if you can accept the fact that a tree is now a living conscious entity that somehow turns other trees into a living conscious entity capable of using magic and has eyes, a nose, and a mouth even though it does not talk or breath or have lungs or a brain then I think you can let it slide and just accept that it is what it is without knowing the ins and outs of every little detail.

I think that he made this assumption based on his slimes reaction to the danger. While the other ones was scared, his sword made of "pure iron" wasn't. It sloppy, indeed, but not that completely unbased? I guess. The same way you may say "That was dark magic, so don't try to apply the Earth knowledge here", its also possible to say "He used slimes, which can't be explained by our rules". His explaination might be wrong here, but its passable.

Sure. The problem is: how did the slimes know that the elder treant has corrosive magic? That is just deus ex machina.
All of his slimes come from the original ones he first tamed in season 1. They weren't metal or iron. Even if they would've seen an elder treant before the taming and survived, that is still not enough to justify them having this knowledge. They would have to witness the treant obliterating something metallic.

Oh, and by the way:

Ultra-high-purity iron (ABIKO iron 99.9996% purity) has a very low yield strength. It is about as strong as 99.9% pure copper or glod. Depending on strain rate the yield strength is 35-100 MPa. Pure copper is around 70 MPa. And 0.2% offset yield strength is lower than that of 99.99% pure gold: ~70 MPa vs ~85 MPa.
That is 2x lower than bronze alloys and 3 times lower than even the mildest of mild steels.

So.... either the iron slimes aren't all that pure (and therefore vulnerable), or his wakizashi (and other "pure" iron weapons) shouldn't be capable of cutting anything - the edge would become completely blunt just from cutting through the bark.

Welp, I'm not knowledgeable to refute hahaha
All I can even try to say is: Instinct. Like when you enter a place you don't know, but u're sure that this isn't somewhere you must be. Maybe they could feel its elemental affinity (dark) or even as the same way they know exactly what they want to eat when Ryouma feed them and will make them grow. IDK either.

All of his slimes came from the original ones? WRONG!!! setting the fluff slime he recently tamed aside and not even mentioning the bloody slime he buyed. Even the first metal slime was a wild one that he caught and tamed in the mines. And just because they did never see an elder treant doesnt mean they cant feel the danger. Ever heard of instincts?

Even pure copper can cut through wood, while it does get dull quicker then iron it would still be able to do it with relative ease for awhile since it is still much stronger then wood. For comparison, a healthy fingernail has the same tensile strength and slightly lower compression strength as copper, its not weak at all. And since the slimes can change their solid form at will, its more likely that even if they did dull after a few wacks...or even from cutting through the bark...they would just return to their sharper form at will. Not that it would really be necessary since you are forgetting the fact that they are a living being capable of applying an outward force far greater then what its basic tensile/compression strength would be, unlike actual metal. It's like saying humans are weaker then paper because it can cut us...

Go read about ABIKO iron, I believe it is based off that. ABIKO iron has very high purity and is resistant to corrosion.

No, it is wasn't a reference to ABIKO iron.
It is simply a general knowledge that very low carbon iron rusts slower than high carbon steel. However it does rust and react with acids and such. Besides, ABIKO iron is corrosion resistant, not proof. It can still be corroded.

On top of that, they were dealing with corrosion cased by a dark magic spell and not a natural chemical process.

Considering how strong Ryoma is, he could've simply taken a piece of that pavement he made and throw it in the elder treants face. In the end he used blunt weapon anyway.

Just some context on ABIKO iron:
It has a very low yield strength. It is about as strong as 99.9% pure copper or glod. Depending on strain rate the yield strength is 35-100 MPa. Pure copper is around 70 MPa. And 0.2% offset yield strength is lower than that of 99.99% pure gold: ~70 MPa vs ~85 MPa.
That is 2x lower than bronze alloys and 3 times lover than even the mildest of mild steels.

I think you probably want to start noticing the fantasy aspect of the anime, otherwise have fun trying to scrutinize all the physics in anime.

you forgot to consider whatever Ryoma does, it will always work out. Ryoma could throw cake at it and it would still go down.

wow, yield strength similar to copper? that's impressively low for something iron-based.

ABIKO iron isn't "iron based". It is 99.9996% pure iron.
It is only made and used for research. It costs approximately $1 million dollars per kilogram to produce.

In general, the purer the metal is - the "softer" it gets. I don't know if it is true for all metals, but certainly for most of them.

E.g.: pure aluminium (>99.5%) has yield strength ~20-35 MPa, less pure 99.0% has strength 100 MPa.
Only half of a percent difference in purity, yet 3-5 times the strength.

i mean, pure iron is still iron-based, just to the extreme. it seemed a good way to me to neatly put it in a group for comparison with regular iron, the variuous steels, and other alloys.
did not know that most metals get really soft at such purities tho

Impurities act as a structural support system in most metals. For example, if you build a box out of only 2 inch long toothpicks it would be pretty easy to knock over because it has no diagonal supports since they would need to be longer then 2 inches. But if you support the inside of the box with diagonally placed longer toothpicks it would increase the structures rigidity, adding more smaller toothpicks to support that as well increases the structures ability to withstand pressure from all directions. A metals structure is pretty similar, the more gaps in the structure you can fill up, the stronger it becomes (once again, in most cases).

For iron it's base structure is that every iron atom has another to the front, left, right, back, top and bottom.
A cut out of this can be seen as a cube with an iron atom at each corner.
The pure iron makes for a very loose cube that's easily deformed (Think those stick magnets with balls you can use to buid stings with). As such pure iron is soft (no idea how soft as i don't think we ever managed to make it 100% pure). I think the purest we can make is like 'can be cut with a knife if you use enough force'.

If you add carbon, its atoms will go in the center of said cubes stabilising it (one per cube). The carbon will stabilise the cube as it pushes the iron away if it's deformed from a proper cube. As such more carbon will make iron harder.

For being more rust resistant. That seems unlikely as as far as I understand the rust reactions involve the iron and exernal substances, so the presence of carbon probably doesn't really matter. It's not like it's needed for the reaction.

Why exactly did you just comment the same example to me but change the material to explain the same thing? lol

As for rust resistance, some impurities make it easier for an atom to shed its electrons which is the driving force in the corrosion process. While some impurities can slow the process (carbon for example), it has very little impact on iron unless it was deliberately done in a uniform manner. Otherwise the surface spots with bad impurities will just corrode through the areas with good impurities. Impurities deposited on the surface from an outside source will also have a similar impact. Think of it like stirring sugar into coffee, do you need to stir it for it to mix? No, the sugar will eventually disperse throughout the coffee on its own given enough time, but if you stir it it speeds up the process by moving sugar to less saturated areas of the liquid.

It's not the same. While the thing described is the same, your version is all analogy and too little details. I doubt someone that doesn't know about this would get how it actually works.
You never explained about how the atomic structure actually looks and how im this case carbon would make iron hard.
Your description is basically all toothpick and no atoms, so I added this for anyone that might be interested in the details.