You’ve probably seen the discourse online. Some fans called it filler. Others complained about the pacing. But honestly, if you skip over the Demon Slayer: Kimetsu no Yaiba television show season 4, you’re missing the actual heartbeat of the entire series. It’s easy to get distracted by the flashier fights in the Entertainment District or the high-stakes chaos of the Swordsmith Village, but the Hashira Training arc does something those seasons couldn't: it makes us care about the people who are probably going to die soon.
Ufotable is known for pushing the boundaries of what TV animation can actually be. We saw that again here. But this season wasn't just about pretty colors or Zenitsu finally waking up for more than five minutes. It was about the calm before a very literal storm.
The Training Arc That Wasn't Just Training
Most shonen anime handle training arcs with a quick montage and a sudden power-up. Demon Slayer didn't do that. Koyoharu Gotouge’s original manga chapters for this section were notoriously short—only about nine chapters in total. To turn that into a full-scale television production, the team at Ufotable had to expand. They added depth. They gave us moments like the bridge scene with Giyu and Tanjiro that felt heavy, quiet, and necessary.
The Demon Slayer: Kimetsu no Yaiba television show season 4 focused on the Hashira Training. Basically, every remaining Hashira—except for Giyu initially and the retired Uzui—had to lead specialized boot camps. You had Gyomei Himejima pushing people through waterfalls and Sanemi Shinazugawa basically beating the breaks off everyone in the name of "instruction."
It felt different because the stakes shifted from external threats to internal growth. For the first time, we saw the rank-and-file slayers as more than just background characters meant to be eaten by Rui’s family or Upper Moons. We saw them sweating. We saw them eating rice balls. We saw them becoming a cohesive unit. This matters because when the Infinity Castle eventually happens, the loss of these "extras" is going to hurt way more.
Breaking Down the Hashira Dynamics
One of the most humanizing parts of the season was seeing the Hashira interact when they weren't mid-battle. Usually, we only see them when limbs are flying or blood is being spilled. Here, we got to see Mitsuri Kanroji’s infectious (and slightly chaotic) joy during her flexibility training. We saw Muichiro Tokito actually acting like a kid for once, even if he was a kid who could outclass grown men with a wooden sword.
The tension between Sanemi and Genya was particularly brutal. If you’ve been following the story, you know their relationship is a wreckage of trauma and misunderstood protection. Season 4 leaned into that. It didn't give us a neat resolution because life isn't neat. It gave us a glimpse into why Sanemi is so seemingly hateful—he’s desperate to keep his brother away from the very world they're currently training to defend.
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Why the Animation Quality Still Matters
People love to joke that Ufotable has an "unlimited budget." While that’s technically a meme, the visual fidelity in the Demon Slayer: Kimetsu no Yaiba television show season 4 proves that they don't take their foot off the gas even for "slower" arcs.
Look at the environment design. The way the water looked in Gyomei’s mountain training or the lighting during the final confrontation at the Ubuyashiki estate. It wasn't just "good for anime." It was cinema-grade. The final episode of the season—the one where Muzan Kibutsuji finally walks up to Kagaya Ubuyashiki’s front door—was a masterclass in suspense. The sound design alone, the clicking of Muzan's shoes, the way the wind died down. It felt like the air was being sucked out of the room.
That’s why the "filler" argument falls flat. You can't call content filler when it’s directed with that much intentionality. Every frame of Muzan walking through that garden was designed to make you feel dread. It worked.
The Marking of a Slayer
A huge part of this season was the mystery of the Demon Slayer Mark. We learned that these marks aren't just cool tattoos that grant a power boost. They come with a heavy price. Most people who manifest the mark don't live past the age of 25.
Think about that for a second.
Most of the Hashira are already in their early 20s. By choosing to train and manifest these marks, they are essentially signing their own death warrants to ensure Muzan is defeated in this generation. It’s a level of sacrifice that the show handles with a weird sort of quiet dignity. Tanjiro, being the catalyst, doesn't even fully realize the weight of what he’s started. He’s just happy to see his friends getting stronger.
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The Muzan Factor
Let’s talk about the ending. Specifically, that walk. Muzan Kibutsuji has been this looming shadow for three seasons, but in the Demon Slayer: Kimetsu no Yaiba television show season 4, he became a physical presence again. The confrontation between him and Kagaya was the highlight of the year for many fans.
Kagaya Ubuyashiki, a man who is literally rotting away, standing his ground against a "god" was incredible. The dialogue here wasn't about power levels. It was about legacy. Kagaya’s argument that human will is eternal while Muzan’s dream of immortality is a lonely, fragile delusion hit hard. It set the stage for everything that comes next.
And then? The explosion.
Nobody who hadn't read the manga saw that coming. The sheer audacity of Kagaya using himself and his family as bait to catch Muzan off guard changed the tone of the series instantly. It went from a training arc to a war movie in approximately 30 seconds.
The Technical Shifts
Director Haruo Sotozaki made some interesting choices this season. The pacing was deliberately slow at the start. It felt like a slice-of-life show at times. You had the guys competing over who could eat the most or Tanjiro helping people fix their homes.
- Pacing: Slow, then explosive.
- Tone: Melancholic but hopeful.
- Visuals: Heavy use of 3D environments mixed with hand-drawn character acting.
- Score: Go Shiina and Yuki Kajiura leaned more into traditional Japanese instruments to ground the "training" atmosphere.
By the time the Infinity Castle gates opened and everyone was sucked into Nakime’s fortress, the shift in music and animation style was jarring in the best way possible. It felt like falling into a nightmare.
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Common Misconceptions About Season 4
I hear people say that nothing happened this season. That’s objectively wrong. A lot happened, just not in the way of "big bad demon gets head cut off."
First, Zenitsu’s character shift. If you noticed, toward the end of the season, he stopped screaming. He received a letter. He became somber. For a character defined by his cowardice, this silence is deafening. It’s a massive plot point that sets up his arc in the upcoming films.
Second, the relationship between Giyu and the rest of the corps. Giyu’s "I am not like you" wasn't arrogance; it was survivor's guilt. Tanjiro breaking through that shell was the most important emotional beat of the season. Without that, the Hashira wouldn't be fighting as a unified front. They’d be a collection of powerful individuals, and as Kagaya pointed out, that’s not how you beat Muzan.
What This Means for the Future
The Demon Slayer: Kimetsu no Yaiba television show season 4 served as the final bridge. We now know that the story won't continue as a traditional TV season. Instead, we’re getting a trilogy of films covering the Infinity Castle arc.
This is a bold move. It means the "quiet" moments we got in Season 4 are the last ones we’ll ever get. From here on out, it is pure, unadulterated conflict. The training we watched Tanjiro and the others endure is the only reason they’ll have even a slim chance of surviving what’s inside that castle.
Actionable Takeaways for Fans
If you’re looking to get the most out of your rewatch or preparing for the movies, keep these things in mind:
- Watch the backgrounds. Ufotable hides a lot of foreshadowing in the scenery and the way certain characters look at each other.
- Pay attention to the letters. The correspondence between characters this season (like the one Zenitsu got) is vital for the next arc.
- Notice the marks. Keep track of who has manifested their Slayer Mark and who hasn't. It changes the power dynamics of the upcoming fights significantly.
- Listen to the breathing. The sound design for the different breathing styles became much more distinct this season as the slayers refined their techniques.
The Hashira Training arc was the deep breath before a plunge into darkness. It wasn't a detour; it was the foundation. Without the character work done here, the upcoming deaths and victories would feel hollow. Instead, we’re going into the finale knowing exactly what these people are fighting for—and exactly what they’re willing to lose.
Before the movies drop, go back and watch the final two episodes of Season 4 again. Look at the faces of the Hashira as they fall into the Infinity Castle. That mix of terror and determination is exactly what this season was trying to build. You're now ready for the end.