Warning: The following article contains major spoilers from Demon Slayer manga. Read ahead at your own discretion!

Zenitsu might be annoying and weak at first but he eventually becomes one of the most useful characters in Demon Slayer. I mean, I’m pretty sure Tanjiro, Tengen, and the others wouldn’t have won against Gyutaro in the Entertainment District arc if Zenitsu had not used Godspeed to slice Daki’s head off. The memory of fans screaming in the theatre while this scene came up is pretty vivid in my brain.

Anime-only fans, you haven’t seen the complete might of Zenitsu just yet. The Infinity Castle arc is where he masters his Thunder Breathing technique to such an extent, he whips up a form of his own called “Honoikazuchi no Kami”!

Just how strong did Zenitsu become towards the end of Demon Slayer? Well, you’re in the right place cause’ it’s time to break down the character in terms of his traits!

But first, let’s get a few routine questions out of the way.

Did Zenitsu Agatsuma become a Hashira?

No. Currently, there’s nobody occupying the role of Thunder Hashira even after the end of the Infinity Castle arc, as Zenitsu is nowhere close to the experience and strength of the Hashiras, so the spot stays vacant.

The spot was last occupied by his master Jigoro Kuwajima and he hadn’t picked a successor because Zenitsu wasn’t strong enough and his other student, Kaigaku became an Upper Rank 6 Demon.

Zenitsu always had poor luck with women and never had parents so the only option he had left to clear his debt was to become a demon slayer with his sensei’s help.

In this scenario, Zenitsu is clearly uncomfortable with the situation, and Kaigaku isn’t pleased either. Kaigaku criticizes Zenitsu for wasting their Sensei’s time, and gets particularly angry when Zenitsu calls him ‘gramps’. Kaigaku uses this rage to play up Zenitsu’s insecurities in an effort to persuade him to leave the dojo by undermining his skills.

Zenitsu once climbs a tree to escape Jigoro, but lightning strikes him, turning his hair yellow.

When Tanjiro first meets Zenitsu, he has to pull him away from a girl whom Zenitsu is desperately asking to marry because he believes his days are numbered as a demon slayer, which fuels his frantic plea. Despite his troubles with women, Zenitsu remains a major SIMP, frequently seen as a coward by Tanjiro and others since he prefers to avoid fighting and tries to escape.

Zenitsu’s journey unfolds across different story arcs, focusing on him overcoming his panic attacks and anxiety, which often prevent him from showcasing his true strength.

Ultimately, Zenitsu was always stronger and more talented than Kaigaku, even during their time at the dojo. However, his lack of confidence made him feel inadequate. His confidence gradually improves through his work with Tanjiro and the various events they experience together in the story.

So let’s get to the crux of what we’ve come here for.

How Strong is Zenitsu Agatsuma in Demon Slayer?

Zenitsu became a Thunder Hashira level also thanks to his two unique powers, one of which was his extremely enhanced sense of hearing.

Hearing

To describe just a few of his feats, when we first see his abilities shown and described, is in the Tsuzumi Mansion arc. He first hears sounds from very far away, sounds that haven’t even registered for Tanjiro yet.

In fact, Zenitsu’s hearing ability is so enhanced that he can even recreate sounds he hears on instruments immediately as shown in chapter 72.

Zenitsu can hear through multiple layers of walls to decipher specific voices.

Using this ability he is able to discern humans from demons, as is shown when he says that he knew Tanjiro was carrying a demon all along, this is also where we learn that he can hear people’s true selves through the sound of their heartbeat and their blood contracting, as he describes Tanjiro as having the kindest sound he’s ever heard.

Zenitsu can even tell when someone is lying and whether they’re trustworthy or not, despite this ability, he was tricked because he still trusted people that he wanted to, hinting at his kind nature. This is why his story of being a simp is so sad, since he knew the women didn’t like him but still signed up to their onlyfans, getting all bricked up for nothing.

His hearing is so finely tuned that he can detect the presence and strength of both demons and humans. This ability is demonstrated when he instantly recognized Daki as a demon and identified her as an upper rank.

Remarkably, his acute hearing enables him to fight even while unconscious and with his eyes closed, as he can perceive his environment and sense what others are thinking. He can even hear the physical injuries of people, such as when Tanjiro headbutts Inosuke and Zenitsu can actually hear the sound of his ribs breaking.

As Inosuke mentions in Chapter 91, Zenitsu fights the best when he’s asleep and that’s when he can use his Thunder Breathing techniques to its utmost proficiency. These techniques are what defines the strength of a Demon Slayer and Zenitsu is no exception. Let’s try to understand them briefly.

Thunder Breathing techniques

According to Zenitsu, this breathing style is all about directing power into the legs and harnessing the full potential of each and every one of their muscles and blood vessels. This helps in building up the strength in one’s legs and lets him/her to run at a speed that cuts the air like a thunderclap.

This was how Tanjiro was able to use Thunder Breathing to reach Hantengu in the Swordsmith Village arc.

(Demon Slayer Chapter 125)

A perfect user of this technique is fully conscious of the body’s dimensions and muscle shapes, basically utilizing each and every ounce of the muscle fibers to zoom through. In such a state, they cause the air to vibrate when poised to unleash a technique and create immensely loud sounds akin to thunder with their mere footsteps.

Despite this Tanjiro admits to Zenitsu later on that his version of the Thunder Breathing techinque wasn’t on Zenitsu’s Level, which means that Zenitsu is insanely fast, even surpassing Tanjiro’s Sun Breathing and Water Breathing techniques at the time, as Tanjiro chose to copy Zenitsu’s technique rather than use Sun Breathing or Water Breathing.

Totaling six forms, Thunder Breathing is said to have its roots in the first form. Nevertheless, Zenitsu created a Seventh Form so he could compete on an equal footing with Kaigaku, who had risen to the position of Upper Rank Six of the Twelve Kizuki.

Apart from the 7th form, Zenitsu has merely created variations of the 1st form but the technique was OP enough for Zenitsu to bust through demons with mastering just the first form.

In terms of basic power scaling, it’s evident that Tanjiro ranks as at least the fifth strongest character in the series. However, Zenitsu surpasses him in speed, even as the story progresses. This suggests that Zenitsu possesses certain attributes that elevate him to the level of the Hashira.

Zenitsu’s extraordinary ability is first showcased in chapter 23, where he uses Thunder Breathing: First Form ‘Thunderclap and Flash’ to behead a demon, stunning everyone, including himself. It is later revealed that Zenitsu can only perform the first form of Thunder Breathing, out of a total of six unique forms.

Given this limitation, one might assume Zenitsu to be weaker compared to Tanjiro and Inosuke, potentially even useless, as the spider demon suggests in chapter 33. However, this assumption would be incorrect. Despite being able to utilize only the first form, Zenitsu has perfected it to an extraordinary degree. He has developed variations of this technique to enhance his speed and power. An example of this is ‘Thunderclap and Flash: Sixfold,’ which he employs in chapter 34 to defeat the spider demon by executing the technique six times in quick succession, significantly boosting his speed and power.

This mastery and relentless practice reflect the wisdom of Bruce Lee, one of history’s greatest martial artists, who famously said, “I fear not the man who has practiced 10,000 kicks once, but I fear the man who has practiced one kick 10,000 times.”

In the Mugen train arc, Zenitsu learns ‘Total Concentration Breathing : Constant’ which all Hashira use, and as Rengoku says to Tanjiro, its the first step to reaching Hashira.

This technique allowed Zenitsu to use Thunder Breathing to an even greater extend, in this arc we see that Zenitsu truly has natural talent, as Tanjiro trained for a week longer than him to break the gourd, but Zenitsu catches up extremely quickly, exploding the gourd with his breath at the same time as Tanjiro.

Showcasing that Zenitsu required less time to master a hashira level technique, this is why the build up to his NEW 7th form of the thunder breath made sense because if he has the correct motivation, he can achieve the most insane levels of power.

But that doesn’t stop here. In the Entertainment District arc, Zenitsu unlocks 2 new forms of Thunder Breathing, possessing God-like speed to catch upto Daki and slices her head off with the help of Inosuke.

But the biggest FEAT we’ve ever seen of the young Demon Slayer is in the Infinity Castle arc where he creates his own Thunder Breathing technique to finish off Kaigan.

This development is more significant than it seems at first glance. Only true masters of a particular breathing style can create a completely new technique, and this is almost unheard of outside the elite Hashira ranks. Even among the Hashira, it is a rare accomplishment, with Giyuu being a notable example, having developed the 11th form of water breathing.

As Kaigaku falls, his insecurities are brought to the forefront, believing that Zenitsu was his Sensei’s favorite and the only one taught this new technique. Zenitsu quickly clarifies that he invented the technique specifically to be Kaigaku’s equal.

This indicates that Zenitsu has already achieved a power level on par with the Hashira! However, by the end of Demon Slayer, he surpasses even this level in certain respects, demonstrating further growth and prowess against the Demon King Muzan.

This is the first fight in the series where we see how truly capable Zenitsu is when he’s focused and awake, Zenitsu is usually asleep whilst fighting, but as I said earlier, to fight whilst asleep he focuses fully on his sense of hearing, but now he can see as well as using that ability to its fullest.

We also witness his development with his other technique, ‘Thunderclap and Flash: Godspeed.’ Before the Hashira training arc, an unconscious Zenitsu remarked that he shouldn’t use this technique more than twice. However, during the battle against Muzan, we see him employ it multiple times despite being injured and even using his seventh form again. Remarkably, he fights on par with the Hashira, despite not having the mark.

Moreover, Zenitsu doesn’t possess the red blade that enhances and aids the other Hashira in damaging Muzan. Yet, even without these advantageous powers, he manages to outpace the Demon King.

If Zenitsu had the Red Crimson Blade to stop Muzan’s regeneration, he could have used his seventh form to destroy all of Muzan’s hearts. With the Demon Slayer Mark, he could have utilized the transparent world to target them all or relied on his supernatural hearing to pinpoint each of Muzan’s heartbeats.

Due to his technique and training, his other stats improved drastically as well, including his durability!

Endurance / Durability

Zenitsu’s body had taken quite the beating during his battles, including broken ribs and even gets thrown out of a second story building! However, after the Entertainment District arc, he recovered slightly earlier than Tanjiro, who was out for literally two months.

His body became so sturdy that he was not only able to withstand even Muzan’s tentacle attacks, which could reduce entire buildings into rubble, but also comeback immediately for a counterattack.

Due to his intensive training in the Hashira Training arc, which included sitting under a waterfall, carrying logs on his back, pushing a boulder, and various other things, his body is now able to withstands a slow-acting poison and still fight despite puking up blood, and performing Thunder Flash First Form: Sixfold in this state.

He was able to slow down the poison through breathing techniques, and fights with Muzan caused him these many injuries but he became so mentally strong he ain’t such a pussy anymore. Normally, even a minor inconvenience or bleeding would make him cry out but after all these events, he grew mentally and physically as well.

Of course, the biggest feat in this category is him surviving a literal bolt of lightning, which merely changed his hair from black to yellow. While the average lightning strike contains around 300 million volts, superbolts are 1,000 times stronger and can cause major damage to infrastructure and ships, let alone kill humans. And if Zenitsu was able to survive that, then nothing else can be said about his immense durability.

This single event changed his life forever, making him move as quickly as sound itself.

Speed/Agility

We’ve already talked about how fast he was with other demons but what comes to mind in terms of the strongest is obviously Muzan and in the midst of fighting the other Hashiras, Zenitsu moved so fast that even Muzan couldn’t track his movements unless he focus all his energy into finding him.

With that speed, Zenitsu was able to do what the other Hashiras couldn’t: cut off the most of Muzan’s tentacles and that’s an achievement he’d talk to his kids for generations!

In one other occassion, he produced strike five times in the blink of an eye. The duration of a blink is on average 100–150 milliseconds, which is basically the fastest muscle in the body. Even the brain takes longer to process all of it, which is already faster than the speed of sound.

Zenitsu might actually be the fastest in the entire series. So there you go, he ain’t so weak after all!