3 Worst Things About Demon Slayer: Infinity Castle (Despite its Huge Success)

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The popular manga *Demon Slayer* by Koyoharu Gotouge finished in 2020, and the anime is now continuing the story with a series of three movies focusing on the Infinity Castle Arc. The first movie came out in Japan on July 18, 2025, and then in U.S. theaters on September 12, where it had a hugely successful opening. As the story progresses, the battle against the demons becomes even more dramatic inside the seemingly endless Infinity Castle. After the Hashira Training Arc, the Demon Slayers finally find Muzan Kibutsuji, but their attempt to defeat him is interrupted when Nakime, a demon who plays the biwa, traps the entire Corps within the castle.

The story’s final section splits into two main parts: the Infinity Castle Arc and the Sunrise Countdown Arc. Currently, only the Infinity Castle Arc is planned for adaptation in the upcoming trilogy, although this hasn’t been officially confirmed. While this arc is exciting and develops the characters further, it wasn’t universally loved when it was first released, receiving mixed reactions from fans – though opinions improved over time. Now that the anime is covering the entire final section, viewers will likely encounter the parts that were considered weakest in the original story, and these issues can’t be fixed with the adaptation. Early previews also suggest the anime won’t follow the source material exactly.

Warning: This article contains spoilers from the Demon Slayer manga!

3) Unanswered Questions About the Demon Slayer Mark’s Curse

After the Sengoku period, details about the Demon Slayer Mark were lost to time. During that era, Demon Corps members were still mastering breathing styles under Yoriichi Tsugikuni, who himself possessed the mark. He had a unique ability to help others awaken their own marks, almost like a shared connection. Centuries later, in the Taisho Era, Tanjiro joined the Corps and, like Yoriichi, had the same mark and breathing technique. This is why the Hashira were able to unlock the power of the Mark.

Awakening the Mark grants incredible power, but comes with a terrible cost: those who unlock it are destined to die before their 25th birthday. During the chaotic Sengoku Era, Demon Slayer deaths rose sharply, and it’s unknown if these warriors fell in combat or were killed by the Mark itself. After defeating Upper Rank Four and Five, Shinobu Kocho and Muichiro Tokito observed that activating the Mark is essentially challenging fate and inviting an early death.

I watched as, besides Tanjiro, only the Hashira developed their Marks, but sadly, most didn’t survive the final battle – only Giyu and Sanemi were left standing. It made sense that Tanjiro lived, considering his Mark resembled Yoriichi’s, but what happened to Giyu and Sanemi remained a question. They were both just 21 during the fight, and we never found out if they lived past 25. A lot of fans believe the curse ended when Muzan was defeated, but the truth about where it even *came* from is unclear – it’s never confirmed if it was even connected to Muzan in the first place.

2) The First Part Excluded a Key Scene From the Manga

During the fight between Akaza and Giyu and Tanjiro, the anime skipped a powerful moment that showed how determined Giyu was. In chapter 154 of the manga, Tanjiro falls due to his injuries, leaving Giyu to fight Akaza by himself. Even though Giyu was seriously hurt, he didn’t give up. The situation was especially dangerous because Akaza wouldn’t stay defeated – he could fully heal while Giyu and Tanjiro were struggling to even move.

In the manga, Giyu remembers his sister and Sabito, still feeling responsible for not being able to save them. He firmly decides he won’t let anyone he cares about die again – he’s specifically thinking of Tanjiro. This highlights his strong determination and strengthens his connection with Tanjiro. The manga scene then immediately shows Koyuki reaching for Akaza’s hand. However, the anime changes this, showing Giyu telling Akaza that he should be the one to fight first, protecting Tanjiro. This alteration makes the moment less emotionally impactful.

The adaptation loses some of Giyu’s strength and the connection he shares with Tanjiro by leaving out his thoughts. The movie already made small changes from the original story, like cutting a scene of baby Hakuji, but this change felt particularly important. As more of the final story is adapted, fans hope future installments will keep these internal thoughts, which show what the characters are really thinking and feeling.

1) Several Character Deaths Happened in a Short Span of Time

Whether a story arc or the overall narrative is successful isn’t about *how many* characters die, but *how* those deaths are portrayed. *Demon Slayer* really excelled with Rengoku’s death in the Infinity Train Arc. It was handled perfectly – the emotional impact was strong, the depth of feeling was significant, and the conclusion felt right. This was likely because the entire arc centered around him.

The final storyline featured intense battles where every character faced a strong opponent. However, characters died so quickly that readers didn’t have time to react or feel the impact of their losses. These abrupt deaths sparked significant criticism during the manga’s release, and understandably so. Losing over half the main characters, particularly beloved ones, was never going to satisfy most fans.

Characters like Shinobu, Muichiro, Genya, Gyomei, Obanai, and Mitsuri are all fan favorites, and the anime can’t avoid the fact that some of these beloved characters will die in the final battle. However, the anime could have made these deaths more meaningful by adding longer or even new scenes. A TV series format would have allowed for this, but the fast pace of a movie doesn’t really allow for such detailed moments.

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2025-09-18 00:11