Demon Slayer: Infinity Castle Movie Finally Solves a Huge Decade-Old Mystery

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The first movie in the *Demon Slayer: Infinity Castle* trilogy is now in theaters, bringing the exciting climax of the series to anime fans. Following last season’s *Hashira Training* arc, which prepared the Demon Slayers for a final showdown, this film focuses on the immense power of Muzan Kibutsuji’s Upper Moon demons. It showcases the Demon Slayers struggling and growing stronger as they gear up for their ultimate battle against Muzan. This first installment contains three major fights, two of which have already concluded.

Warning: This article contains spoilers from the Demon Slayer: Infinity Castle Part 1

Shinobu Kocho’s fight with Doma sadly resulted in her death, but the other battles brought important progress for Tanjiro Kamado and Zenitsu Agatsuma. Zenitsu surprised everyone by developing a new fighting style, but the biggest development came from the fight between Tanjiro, Giyu Tomioka, and Akaza: Tanjiro became significantly more powerful. This strengthens his position as the main hero as the story heads towards its conclusion and finally explains the meaning of the Demon Slayer mark that appeared during his training.

Demon Slayer: Infinity Castle Reveals Answers About Tanjiro’s Demon Slayer Mark

Tanjiro Kamado, the main character, initially explained a mark on his forehead as a burn scar. After his training, this scar changed into a unique symbol. Rengoku’s father revealed during the *Mugen Train* arc that this mark sometimes appears on naturally gifted Demon Slayers, hinting that Tanjiro was born to fight demons. However, a power boost Tanjiro received in the first part of the *Infinity Castle* arc revealed the true origin of the mark, proving his path wasn’t completely predetermined.

As Akaza dominates Tanjiro and Giyu in their fight, Tanjiro understands that simply wanting revenge won’t be enough to win. He needs to find a deeper strength to overcome Akaza’s defenses. He remembers a peaceful night with his father, watching him defeat a bear with incredible speed. Tanjiro now realizes his father acted without anger or aggression, and understands he must fight the same way. This realization unlocks a new power within him, known as the “Selfless State” or the “Transparent World.”

It’s remarkable that Tanjiro mastered such a powerful fighting style just by observing his father. This technique actually originated with their ancestor, Sumiyoshi, who learned it from the enigmatic figure with the Hanafuda earrings and the Demon Slayer mark – a character we met earlier in Season 3. This knowledge was passed down through the Hinokami dance. Tanjiro, watching his father perform this dance as a child, was unknowingly learning a core Demon Slayer technique. Because of this early exposure, he was able to instinctively use the technique when he began his formal training, ultimately awakening his Demon Slayer mark much faster than most.

Other Demon Slayers Will Soon Follow Tanjiro’s Power Upgrade

When Tanjiro first developed his unique mark, it seemed like he was the only one capable of it. But other Demon Slayers, including the Hashira, started showing marks of their own. Tanjiro’s mark appeared because of his father’s Hinokami dance, and using that technique in battle likely helped the Hashira understand and unlock their own marks. Now that Tanjiro has become even more powerful, it’s probable that other Demon Slayers will also gain this ability, especially with the increasingly dangerous threats they face.

The second part of *Demon Slayer: Infinity Castle* will feature fights against the powerful Upper Moon Ranks Two and One, meaning the Hashira will need all the help they can get. Because communication is simple thanks to the crows, Tanjiro can easily teach them a new technique, and the skilled Hashira should be able to learn it quickly. The first movie in the *Infinity Castle* arc not only solved a long-standing mystery about Tanjiro, but also showed how well-developed his character is – a welcome change since many heroes in action anime can feel similar to each other.

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2025-09-19 17:11