Infinity Castle Didn't Give Fans

The Infinity Castle arc in Demon Slayer is one of the franchise’s most breathtaking storylines, delivering nonstop action, devastating losses, and unforgettable duels. Still, even with all its epic clashes, fans can’t help but imagine what could have been if certain dream battles had actually made it to the screen. The story left behind several matchups that could have been legendary.

These “what-if” scenarios are not just fan daydreams, they would have deepened the emotional weight of the arc while highlighting character growth. Whether it’s Hashira confronting demons that perfectly mirror their fighting styles or past rivalries being resolved in battle, these lost opportunities sting. These are the ten biggest Demon Slayer fights that Infinity Castle and the franchise as a whole never gave fans but absolutely should have.

Muichiro vs. Rui

Muichiro falling into the Infinity Castle

Muichiro Tokito, the Mist Hashira, never got a chance to face Rui, the Lower Moon Five who nearly wiped out Tanjiro’s group on Mount Natagumo. Both characters represent youth and prodigious talent. Rui was among the youngest demons to rise through Muzan’s ranks, while Muichiro became a Hashira at only fourteen. A fight between them would have been a true clash of child prodigies.

Their battle would also highlight how different choices shape destiny. Rui succumbed to loneliness and fear, twisting his family bond into something grotesque. Muichiro, despite losing his memory and family, still chose compassion and honor. Seeing his mist techniques clash against Rui’s deadly threads in Demon Slayer could have been both heartbreaking and visually mesmerizing, offering fans a fight grounded in tragedy.

Gyomei vs. Akaza

Demon Slayer Infinity Castle Movie Gyomei Himejima

Gyomei Himejima, the Stone Hashira, is canonically the strongest of the Hashira. Akaza, on the other hand, is the most powerful of the Upper Moons outside of Kokushibo. Both men share a tragic similarity, as they were incredibly strong even before demon or Hashira transformations. Akaza, in particular, was a martial artist who became a demon after unimaginable loss.

A showdown between them would have tested the limits of brute force and martial skill. Gyomei’s massive strength combined with his use of chained axes and spiked flails could have been a perfect foil to Akaza’s lightning-fast martial arts. The thematic weight of seeing two peak warriors, one who chose humanity and one who abandoned it, would have made this battle unforgettable.

Tengen vs. Nakime

Nakime playing instrument in the Demon Slayer anime, hiding her face behind her hair while she plucks the strings.

Tengen Uzui, the flamboyant Sound Hashira, never got his due after retiring following the Entertainment District arc. Infinity Castle could have given him a worthy sendoff with a clash against the dangerous Nakime, the eerie demon who controls the castle itself with her biwa. The idea of a “sound vs. sound” duel is too good to ignore.

Tengen’s explosive sound-based techniques would have directly contrasted Nakime’s eerie, rhythm-driven ability to manipulate the battlefield. Imagine Tengen dodging shifting rooms and flying walls while using his bombs to disrupt Nakime’s tempo. Beyond spectacle, this fight could have given Tengen redemption, proving he was still a capable warrior even in retirement. Fans deserved that closure.

Sanemi and Obanai vs. Akaza

Demon Slayer Hashiras Obanai and Sanemi encounter the Infinity Castle for the first time

Akaza’s duels always carried incredible weight, but one missing matchup could have been monumental, and that is Sanemi Shinazugawa, the Wind Hashira, and Obanai Iguro, the Serpent Hashira, teaming up against him. Both fighters are known for their relentless, unyielding combat styles, which would have pushed Akaza’s limits like never before.

This battle would have explored teamwork against Akaza’s lone-wolf nature. Sanemi’s ferocious wind techniques paired with Obanai’s serpentine strikes would have forced Akaza to adapt in ways fans never saw in his canonical fights. While Tanjiro and Giyu ultimately provided a brilliant duel, this alternate version would have emphasized Hashira unity, showing how two specialists could nearly topple an Upper Moon together.

Mitsuri vs. Daki

Mitsuri runs to the Ubuyashiki mansion in Demon Slayer's finale. — Mitsuri runs to the Ubuyashiki mansion in Demon Slayer’s finale.

Mitsuri Kanroji, the Love Hashira, thrives in a world that often pits beauty against strength. A battle between her and Daki, one of the most striking yet deadly demons, could have perfectly reflected this theme. Both women are renowned for their captivating appearances, but their contrasting philosophies on love and power would have made the fight emotionally gripping.

The clash would also serve as a visual spectacle. Mitsuri’s whip-like sword could dance against Daki’s devastating obi belts, creating fluid and dazzling choreography. Beyond combat, Mitsuri’s warmth and empathy could have provided a sharp emotional counter to Daki’s cold vanity. This battle would have been the ultimate “beauty vs. beauty” showdown with devastating stakes.

Giyu vs. Gyokko

The Water Hashira Giyu Tomioka from Demon Slayer surrounded by a swirl of water

As the Water Hashira, Giyu Tomioka often embodies calm strength and adaptability. Facing Gyokko, the grotesque Upper Moon Five who also manipulates water-like forms, would have been a natural duel. Their abilities could have mirrored and clashed in ways that explored the beauty and corruption of water as an element.

Gyokko’s horrifying vase summons and distorted aquatic creations would have stood in stark contrast to Giyu’s precise, elegant techniques. The fight could have symbolized how the same element can embody serenity or chaos, depending on its wielder. It would also have given Giyu a fight where he wasn’t overshadowed by Tanjiro, allowing his mastery of water to fully shine.

Gyomei vs. Kaigaku

Kaigaku in Infinity Castle — Demon-Slayer-Infinity-Castle-Kaigaku

Gyomei’s story is deeply tied to the orphans he once protected, which makes a hypothetical battle against Kaigaku especially compelling. Kaigaku, Zenitsu’s fallen senior, represents betrayal, cowardice, and wasted potential, which are all things Gyomei despises. A showdown between them could have carried heavy emotional weight tied to Gyomei’s sense of justice.

Kaigaku’s corrupted Thunder Breathing style would have clashed brilliantly against Gyomei’s raw power and stone-based techniques. The fight could have been framed as a moral judgment, with Gyomei delivering justice not just for Kaigaku’s victims but also for the ideals he betrayed. Watching the strongest Hashira crush someone who abandoned humanity for greed would have been cathartic revenge.

Shinobu vs. Gyutaro

Shinobu Kocho charging at Doma using her Nichirin Sword

Shinobu Kocho, the Insect Hashira, is one of the most intelligent fighters in Demon Slayer. Her reliance on poisons and speed could have been tested perfectly against Gyutaro, the venomous, plague-like demon of the Entertainment District. Both use toxins in battle, but for very different reasons, like Shinobu for precision and justice and Gyutaro for cruelty and destruction.

The fight could have played out as a chess match of poisons and countermeasures. Gyutaro’s scythe strikes laced with venom would clash with Shinobu’s quick stabs delivering insect-based toxins. Beyond combat, the philosophical contrast between Shinobu’s desire to heal others through vengeance and Gyutaro’s twisted envy of humanity would have elevated the battle into something chillingly poetic.

Rengoku vs. Doma

Doma in Infinity Castle — Demon-Slayer-Infinity-Castle-Doma

Kyojuro Rengoku’s death at the hands of Akaza remains one of the series’ most heartbreaking moments. Yet, fans often imagine how incredible it would have been to see him face Doma, the ice-wielding Upper Moon Two. Fire against ice is a classic clash, and no one embodies flame’s spirit better than Rengoku.

This battle would not only have been visually dazzling but also emotionally devastating. Rengoku’s fiery optimism would stand in stark contrast to Doma’s icy apathy. The fight could have symbolized passion against emptiness, life against lifelessness. Given Rengoku’s fate, such a duel might have been his ultimate showcase, further cementing him as one of the series’ most beloved Hashira.

Tanjiro vs. Kokushibo

Image of Demon Slayer character and member of the Twelve Demon Moons Kokushibou standing menacingly in front of a full moon.

Finally, the dream matchup many fans wanted: Tanjiro Kamado against Kokushibo, Muzan’s right-hand man and Upper Moon One. Kokushibo represents the ultimate fallen swordsman, a mirror of what Tanjiro could have become had he chosen power over humanity. Their duel would have symbolized the struggle between legacy and corruption.

Tanjiro’s Sun Breathing techniques against Kokushibo’s Moon Breathing could have delivered one of the most breathtaking fights in the franchise. More importantly, it would have allowed Tanjiro to test himself against the ultimate swordsman, proving that compassion and resilience can triumph over centuries of hatred. This missed battle remains one of Demon Slayer: Infinity Castle’s biggest “what-ifs.”