Zenitsu Agatsuma Speed Revision – Light Speed to FTL Evaluation

[Davide_Camarda]

Hello everyone,
I’d like to present a structured analysis supporting the possibility of Light Speed to FTL scaling for Zenitsu Agatsuma in Kimetsu no Yaiba.
This thread combines databook statements, contextual feats, and comparative scaling within the verse.
All calculations and extended reasoning can be found in my blog:

https://vsbattles.fandom.com/wiki/User_blog:Davide_Camarda/Zenitsu_Speed_and_AP_Scaling

https://vsbattles.fandom.com/wiki/User_blog:Davide_Camarda/Zenitsu_FTL_Speed_scaling

Databook Context:​

The official Kimetsu no Yaiba Databook describes Zenitsu’s Seventh Form as “light speed.”
The databook doesn’t just throw the term “light speed” casually — it also emphasizes that Zenitsu’s movements occur “in an instant,” and that other characters are completely unable to follow his attacks visually. Zenitsu’s Thunderclap and Flash techniques have always been portrayed as incredibly fast, but the Seventh Form is described as transcending his previous limits entirely. Between the databook wording and the manga panels showing total motion blur and delayed reactions from others, the intent seems clear: the author wanted to portray the form as operating at an extraordinary, possibly light-speed level

Feat-Based Scaling (Without Statements):​

Even ignoring the databook, Zenitsu’s feat against Kaigaku supports FTL interpretations.
Kaigaku’s Blood Demon Art is based on lightning, and his techniques are explicitly faster and more destructive than Zenitsu lightning, which travels at roughly Mach 880–1000 (assuming massively hypersonic + for Kaigaku, the actual vsbw Scaling)
During their fight, Zenitsu blitzes Kaigaku to the point where he cannot even perceive his movement — a classic perception blitz scenario
Using a multiplier (x1000), Zenitsu’s movement during the Seventh Form would be:
Lowball: 1.1× light speed (FTL) more accurate speed
Zenitsu blitz kaigaku

This also aligns with the broader narrative scaling — Zenitsu is stronger and faster than Kaigaku, who ranks as an Upper Moon.
Later characters such as Muichiro and Tanjiro surpass these feats, maintaining internal consistency within the verse.

Counterarguments and Responses​

“It’s a metaphor.”
While possible, the consistent portrayal of Zenitsu’s Seventh Form as instantaneous and imperceptible strengthens the literal interpretation.

“It breaks scaling consistency.”
The feat only applies to high-end characters using marked forms or heightened breathing states; it doesn’t affect baseline scaling across the verse.

“No visual proof in the anime.”
Animation cannot realistically portray light-speed movement, so scaling relies on textual evidence and comparative feats, which remain consistent.

Conclusion:​

Even using a conservative lowball interpretation, Zenitsu’s Seventh Form logically reaches Light Speed levels, with mid and high-end interpretations extending to FTL and beyond.
This is further supported by the scaling consistency across marked characters and higher-tier demons.
Kaigaku statement

 

[KnyRaizn]

The multiplier for the P.B is too high and unjustified, but I agree with the statement. Although it would still need to be demonstrated that it is not hyperbolic, but it's definitely a good base.

 

[Catbowtie]

This ain't it chief

 

[Epyriel]

The official Kimetsu no Yaiba Databook describes Zenitsu’s Seventh Form as “light speed.”
The databook doesn’t just throw the term “light speed” casually — it also emphasizes that Zenitsu’s movements occur “in an instant,” and that other characters are completely unable to follow his attacks visually. Zenitsu’s Thunderclap and Flash techniques have always been portrayed as incredibly fast, but the Seventh Form is described as transcending his previous limits entirely. Between the databook wording and the manga panels showing total motion blur and delayed reactions from others, the intent seems clear: the author wanted to portray the form as operating at an extraordinary, possibly light-speed level

It doesn't say “light speed” it says “as fast as a flash of light” which is a common expression for just being really fast.

Even ignoring the databook, Zenitsu’s feat against Kaigaku supports FTL interpretations.
Kaigaku’s Blood Demon Art is based on lightning, and his techniques are explicitly faster and more destructive than Zenitsu lightning, which travels at roughly Mach 880–1000 (assuming massively hypersonic + for Kaigaku, the actual vsbw Scaling)
During their fight, Zenitsu blitzes Kaigaku to the point where he cannot even perceive his movement — a classic perception blitz scenario
Using a multiplier (x1000), Zenitsu’s movement during the Seventh Form would be:
Lowball: 1.1× light speed (FTL) more accurate speed
Zenitsu blitz kaigaku

Average lightning speed is accepted on VSBW as 440,000m/s (~Mach 1283), but multipliers (let alone high multipliers over 100x) strictly cannot be used without explicit statements.

All calculations and extended reasoning can be found in my blog:

https://vsbattles.fandom.com/wiki/User_blog:Davide_Camarda/Zenitsu_Speed_and_AP_Scaling

Kinetic Energy cannot be used for lightspeed, as that would require infinite energy.

 

[Davide_Camarda]

It doesn't say “light speed” it says “as fast as a flash of light” which is a common expression for just being really fast.


Average lightning speed is accepted on VSBW as 440,000m/s (~Mach 1283), but multipliers (let alone high multipliers over 100x) strictly cannot be used without explicit statements.


Kinetic Energy cannot be used for lightspeed, as that would require infinite energy.

For the statements:
While “as fast as a flash of light” can sometimes be a figure of speech, the context in Demon Slayer makes it more than a metaphor.

The novelization and anime script both directly describe attacks moving “like a flash of light” in a literal speed comparison, not as a simile for quickness — it’s tied to visual lightning and energy phenomena.

The verse has multiple consistent light-speed references (Zohakuten’s lightning, Kaigaku’s Thunder Breathing, Aizetsu’s light spears), all pointing toward actual light-speed movement, not just hyperbole.

Furthermore, characters reacting to and dodging those attacks makes the comparison functionally literal — otherwise, every character above them would be immeasurably faster, which isn’t consistent with internal scaling.

 

[Davide_Camarda]

It doesn't say “light speed” it says “as fast as a flash of light” which is a common expression for just being really fast.


Average lightning speed is accepted on VSBW as 440,000m/s (~Mach 1283), but multipliers (let alone high multipliers over 100x) strictly cannot be used without explicit statements.


Kinetic Energy cannot be used for lightspeed, as that would require infinite energy.

That’s true for natural lightning, but Kaigaku’s lightning in Demon Slayer is not natural. It’s a demon art-based elemental technique directly tied to spiritual and demonic energy, not atmospheric discharge.

Therefore, its speed is not bound by real-world natural lightning standards.

Similar precedents exist across verses on VSBW (e.g., Naruto’s Chidori, One Piece’s Enel’s lightning, Bleach kido beams) where “lightning-like” or demonic lightning attacks are treated as light-speed or faster-than-natural due to their fictional nature and explicit depiction.

So while real lightning is ~Mach 1000, Demon Slayer’s lightning is clearly supernatural and energy-based, allowing for a higher baseline — and thus scaling it from the “flash of light” phrasing is valid.
This is correct under classical mechanics, but the kinetic energy formula (½mv²) loses validity at relativistic speeds.

In relativistic physics, energy approaches infinity only at exactly the speed of light, but not for sub-light or near-light speeds.

When scaling fictional feats, KE is used as an approximation tool to gauge destructive yield, not literal energy physics.

Furthermore, VsBattles itself uses KE values below lightspeed all the time for quantifying energy tiers — so as long as the velocity is relativistic or FTL but not infinite, the KE calculation remains a consistent comparative measure.

 

[Davide_Camarda]

It is difficult to be Hyperbolic for various reasons
If the author had wanted to mean this in a hyperbolic way, he should not have composed the sentence in this way. Which is as if it were a specification, in fact the sentence begins by saying "The ultimate strike, which is" which translated would be which is, and on a grammatical level it is a specification, as for example I can say, prison break is a series, which is one of the most viewed, it is uncommon for a sentence like this to be Hyperbolic. To give an example, let's say someone wants to express a Hyperbole. Let's take an example, a car passes by you, and what you say is "that car was fast as lightning" or let's say an author wants to make a Hyperbole "with a movement fast as lightning" or something like that. What makes the sentence not favorably hyperbolic, is the fact that no hyperbole would have a specification like that, saying "this technique, which is" is a way of speaking that does not come close to the hyperbolic context in any way. The hyperbole is made clear through the context etc, and it is used in an almost always ironic context, for example a common Hyperbole in Ds is when Tengen says he is a god, given the ironic context and it is clear in the scene. So at the level of how the hyperbole occurs, it is unlikely that it is due to how the sentence is composed.

It doesn't say “light speed” it says “as fast as a flash of light” which is a common expression for just being really fast.


Average lightning speed is accepted on VSBW as 440,000m/s (~Mach 1283), but multipliers (let alone high multipliers over 100x) strictly cannot be used without explicit statements.


Kinetic Energy cannot be used for lightspeed, as that would require infinite energy.

 

[Epyriel]

That’s true for natural lightning, but Kaigaku’s lightning in Demon Slayer is not natural. It’s a demon art-based elemental technique directly tied to spiritual and demonic energy, not atmospheric discharge.

Therefore, its speed is not bound by real-world natural lightning standards.

Similar precedents exist across verses on VSBW (e.g., Naruto’s Chidori, One Piece’s Enel’s lightning, Bleach kido beams) where “lightning-like” or demonic lightning attacks are treated as light-speed or faster-than-natural due to their fictional nature and explicit depiction.

So while real lightning is ~Mach 1000, Demon Slayer’s lightning is clearly supernatural and energy-based, allowing for a higher baseline — and thus scaling it from the “flash of light” phrasing is valid.

You were the one assuming Kaigaku’s lightning was Mach 880-1000, I was merely correcting the number. However Kaigaku’s lightning isn’t currently accepted as real lightning, so this isn’t valid to use either.

This is correct under classical mechanics, but the kinetic energy formula (½mv²) loses validity at relativistic speeds.

In relativistic physics, energy approaches infinity only at exactly the speed of light, but not for sub-light or near-light speeds.

When scaling fictional feats, KE is used as an approximation tool to gauge destructive yield, not literal energy physics.

Furthermore, VsBattles itself uses KE values below lightspeed all the time for quantifying energy tiers — so as long as the velocity is relativistic or FTL but not infinite, the KE calculation remains a consistent comparative measure.

Lightspeed requires infinite energy in both classical and relativistic mechanics.

Which is why using lightspeed as part of a kinetic energy calculation is explicitly banned by VSBW’s Kinetic Energy Rules.

 

[Davide_Camarda]

You were the one assuming Kaigaku’s lightning was Mach 880-1000, I was merely correcting the number. However Kaigaku’s lightning isn’t currently accepted as real lightning, so this isn’t valid to use either.


Lightspeed requires infinite energy in both classical and relativistic mechanics.

Which is why using lightspeed as part of a kinetic energy calculation is explicitly banned by VSBW’s Kinetic Energy Rules.

Yes I am assuming that kaigaku moves at mh+ since we dont know if it is real Lightning. Ok you are right we cant convert sol for KE but we can do it if the character moves for example 93% of the Speed of light relativistic + speed. And I got new proof that scale Zenitsu to it and this confirmed also without the statement that the character is definitely light speed level.
The proof:

Discord - Group Chat That’s All Fun & Games

Discord is great for playing games and chilling with friends, or even building a worldwide community. Customize your own space to talk, play, and hang out.

discord.com

So the statement light speed remain undebankable

 

[Mommyleona]

During their fight, Zenitsu blitzes Kaigaku to the point where he cannot even perceive his movement — a classic perception blitz scenario
Using a multiplier (x1000), Zenitsu’s movement during the Seventh Form would be:
Lowball: 1.1× light speed (FTL) more accurate speed
Zenitsu blitz kaigaku

yeah absolutely no, aint how multipliers work, they need to be stated, especially that big, you also cant upgrade speed from a blitz like that either

 

[Epyriel]

Yes I am assuming that kaigaku moves at mh+ since we dont know if it is real Lightning.

Not allowed to assume that - that is calc stacking.

Ok you are right we cant convert sol for KE but we can do it if the character moves for example 93% of the Speed of light relativistic + speed.

You are not allowed to nerf a speed rating below what it is stated at to use a method that isn’t allowed at the actual value.

And I got new proof that scale Zenitsu to it and this confirmed also without the statement that the character is definitely light speed level.
The proof:

Discord - Group Chat That’s All Fun & Games

Discord is great for playing games and chilling with friends, or even building a worldwide community. Customize your own space to talk, play, and hang out.

discord.com

So the statement light speed remain undebankable

That is a Discord channel link, which we can’t see. You need to post it to something like Imgur if you are trying to share a scan or something.

 

[Kazuma_kuwabara]

 

[Davide_Camarda]

Not allowed to assume that - that is calc stacking.


You are not allowed to nerf a speed rating below what it is stated at to use a method that isn’t allowed at the actual value.


That is a Discord channel link, which we can’t see. You need to post it to something like Imgur if you are trying to share a scan or something.

I ll work ti post It. But what do you think now of the statement i gave you new proofs

 

[Davide_Camarda]

What?

 

[Robo432343]

Agree with FTL, very straightforward

 

[Kaydee1648]

Databook Context:​

The official Kimetsu no Yaiba Databook describes Zenitsu’s Seventh Form as “light speed.”

Ignoring the usage of a simile, the statement is still soundly flowery, and while looking at the whole picture instead of nitpicking, we can see that the statement is just trying to hype the attack as “super fast” or how quickly it can be executed in the “blink of an eye”.

During their fight, Zenitsu blitzes Kaigaku to the point where he cannot even perceive his movement — a classic perception blitz scenario
Using a multiplier (x1000), Zenitsu’s movement during the Seventh Form would be:

Usage of perception blitz as a type of speed multiplier is not tolerated in wiki. Also, the speed difference needed for FTE is just about 6.8 times, and what’s even more absurd is you calling the 1000x lowball.

While possible, the consistent portrayal of Zenitsu’s Seventh Form as instantaneous and imperceptible strengthens the literal interpretation

It really doesn’t when being super-fast aka >subsonic let’s you be perceived as instantaneous by the average person. Being instantaneous can be anything above subsonic, so no, it does not support your premise.

 

[SeijiSetto]

as many have said already
閃光が走りの如く is a simile comparing his movements to a flash of light, not literally saying he moves that speed, and the multiplier is pulled from thin air

 

[BoastJr]

Y'all need to accept that Demon Slayer is a John Fart Attack victim

This is the Same Verse to lose a 9 v 1 Against the Goat Deku... if it were me I'd pack it up, change countries and quit

This shit is wild dawg idk what to tell y'all

 

[FriendOfTheTeaParty]

shout out to ChatGPT for writing for the OP

 

[CastoriceTheFifth]

Y'all need to accept that Demon Slayer is a John Fart Attack victim

This is the Same Verse to lose a 9 v 1 Against the Goat Deku... if it were me I'd pack it up, change countries and quit

This shit is wild dawg idk what to tell y'all

You act like KNY supporters wrote this crt

 

[Davide_Camarda]

Ignoring the usage of a simile, the statement is still soundly flowery, and while looking at the whole picture instead of nitpicking, we can see that the statement is just trying to hype the attack as “super fast” or how quickly it can be executed in the “blink of an eye”.

Usage of perception blitz as a type of speed multiplier is not tolerated in wiki. Also, the speed difference needed for FTE is just about 6.8 times, and what’s even more absurd is you calling the 1000x lowball.

It really doesn’t when being super-fast aka >subsonic let’s you be perceived as instantaneous by the average person. Being instantaneous can be anything above subsonic, so no, it does not support your premise.

# 2

**Then the databook, being an encyclopedia, it is difficult for hyperbole to be used, or at least they should be made clear, in fact as it is said, the perbole should not be used in encyclopedias. It is like saying that in a book of I don't know, explanation of physics, of living beings or shit like that, there was a hyperbole, when the purpose of the book is only to give information and leave feelings out. Therefore it is very unlikely that it is a hyperbole.

Going into specifics, in Databook 2 it is specifically stated that it collects precise information and things not said in the manga, and indeed a collection of information on everything. And connecting to what is said before in case the author is giving wrong information. And therefore the most logical reasoning is simply to think that the author wants to say that Zenitsu is SOL speed. Or at least it is the most logical choice. I used an other pov for the perception blitz

 

[Davide_Camarda]

Y'all need to accept that Demon Slayer is a John Fart Attack victim

This is the Same Verse to lose a 9 v 1 Against the Goat Deku... if it were me I'd pack it up, change countries and quit

This shit is wild dawg idk what to tell y'all

# 2

**Then the databook, being an encyclopedia, it is difficult for hyperbole to be used, or at least they should be made clear, in fact as it is said, the perbole should not be used in encyclopedias. It is like saying that in a book of I don't know, explanation of physics, of living beings or shit like that, there was a hyperbole, when the purpose of the book is only to give information and leave feelings out. Therefore it is very unlikely that it is a hyperbole.

Going into specifics, in Databook 2 it is specifically stated that it collects precise information and things not said in the manga, and indeed a collection of information on everything. And connecting to what is said before in case the author is giving wrong information. And therefore the most logical reasoning is simply to think that the author wants to say that Zenitsu is SOL speed. Or at least it is the most logical choice.**

 

[Davide_Camarda]

as many have said already
閃光が走りの如く is a simile comparing his movements to a flash of light, not literally saying he moves that speed, and the multiplier is pulled from thin air

**Then the databook, being an encyclopedia, it is difficult for hyperbole to be used, or at least they should be made clear, in fact as it is said, the perbole should not be used in encyclopedias. It is like saying that in a book of I don't know, explanation of physics, of living beings or shit like that, there was a hyperbole, when the purpose of the book is only to give information and leave feelings out. Therefore it is very unlikely that it is a hyperbole.

Going into specifics, in Databook 2 it is specifically stated that it collects precise information and things not said in the manga, and indeed a collection of information on everything. And connecting to what is said before in case the author is giving wrong information. And therefore the most logical reasoning is simply to think that the author wants to say that Zenitsu is SOL speed. Or at least it is the most logical choice.**

 

[Davide_Camarda]

Agree with FTL, very straightforward

Do you agree with the statement?

 

[Kaydee1648]

# 2

**Then the databook, being an encyclopedia, it is difficult for hyperbole to be used, or at least they should be made clear, in fact as it is said, the perbole should not be used in encyclopedias. It is like saying that in a book of I don't know, explanation of physics, of living beings or shit like that, there was a hyperbole, when the purpose of the book is only to give information and leave feelings out. Therefore it is very unlikely that it is a hyperbole.

Going into specifics, in Databook 2 it is specifically stated that it collects precise information and things not said in the manga, and indeed a collection of information on everything. And connecting to what is said before in case the author is giving wrong information. And therefore the most logical reasoning is simply to think that the author wants to say that Zenitsu is SOL speed. Or at least it is the most logical choice. I used an other pov for the perception blitz

Hyperboles are used in databooks all the time.
Taking databooks at face value will have Temari scaling to universal

 

[FriendOfTheTeaParty]

Hyperboles are used in databooks.
Taking databooks at face value will have Temari scaling to universal

maybe she is universal huh

 

[CastoriceTheFifth]

Hyperboles are used in databooks.
Taking databooks at face value will have Temari scaling to universal

What the hell kind of data book are you reading to get universal susamaru

 

[Kaydee1648]

maybe she is universal huh

Right
can’t wait for Temari to solo bleach

 

[BoastJr]

maybe she is universal huh

Snip

 

[Robo432343]

 

[AppleMaker]

Bruh, DS is already overrated af on VSBW and you just pour gasoline into that fire

 

[Ruby_R_Dracula]

Bruh, DS is already overrated af on VSBW and you just pour gasoline into that fire

I didn't wanna interact with anything DS until it finally gets dragged to hell and back like the pitiful worm it is, but man

wtf is this

 

[AppleMaker]

I didn't wanna interact with anything DS until it finally gets dragged to hell and back like the pitiful worm it is, but man

wtf is this

Ngl, I'm glad that their speed was fixed, but 7-C/7-B tiers are ludicrous. Especially when JJK gets constantly downgraded to 7-C, while having MUCH better and straightforward feats. Not to mention that most of those ap feats gets revoked in other verses (Cough cough City level Vox)

 

[Robo432343]

Ngl, I'm glad that their speed was fixed, but 7-C/7-B tiers are ludicrous. Especially when JJK gets constantly downgraded to 7-C, while having MUCH better and straightforward feats. Not to mention that most of those ap feats gets revoked in other verses (Cough cough City level Vox)

????
what
there is nothing wrong with tier 7-C/7-B/ tier 7 DS
thats like the least most controversial thing right now

 

[AppleMaker]

Also I have some problem with battle spirit - does it really incaps opponents and induces fear in them? From what I've seen - it mostly just shows the power level of anyone who isn't in transparent world state, that hides it

 

[CastoriceTheFifth]

????
what
there is nothing wrong with tier 7-C/7-B/ tier 7 DS
thats like the least most controversial thing right now

Man yall really got to decide what the issue is between 7-B or Relativistic because I've seen multiple of yall yapping about "Speed is fine but AP is glaze" or "AP is fine but speed is glaze"

 

[AppleMaker]

"Speed is fine but AP is glaze"

I'm on this side btw

 

[Robo432343]

the ratings are fine unless proven otherwise

 

[CastoriceTheFifth]

the ratings are fine unless proven otherwise

Funny thing is 7-B Relativistic ratings wasnt even the main objective and was just a side quest

 

[Robo432343]

Funny thing is 7-B Relativistic ratings wasnt even the main objective and was just a side quest

ok anything above 7-B and rel is doing too much