Kanao Tsuyuri and Inosuke Hashibira vs Doma is a battle that takes place in the Infinity Castle, between Demon Slayers Kanao Tsuyuri and Inosuke Hashibira and Upper Rank Two Doma. It occurs immediately after Shinobu Kocho's duel against Doma.
As Shinobu is being absorbed by Doma, Kanao Tsuyuri arrives at the scene, and Shinobu manages to signal to her Tsuguko with her hand. Her death causes Kanao to go berserk in order to try and save her, only to be repelled by an irritated Doma, who tells her not to interfere when he's in the middle of absorbing someone. He successfully devours Shinobu's body until her butterfly-shaped hair piece is the only thing left of her.
Doma notes aloud that Kanao must have been told something by the signal her master gave her, wondering what she could have told her, as Kanao stands silently before him.
Shortly after, after Akaza's death, Doma begins to cry for his lost 'friend', but Kanao just tells him to stop it with the lies. She continuously insults him until the Upper Rank's face turns serious.
Suddenly, Doma appears behind Kanao, attempting to use one of his fans to cut her head, but she quickly dodges and delivers a blow to his stomach, causing some of his organs to fall out. He doesn't seem to feel her blow, simply sending some of his ice lotuses at her and noting that her reaction speed has risen as she's able to adapt to his attacks. As he regenerates his body, he thinks to himself that Kanao could actually be stronger than Shinobu, a Hashira.
Trying to suppress her rage, Kanao attacks Doma with the Flower Breathing, Fifth Form: Peonies of Futility, which he avoids with ease, smiling and commenting on how pretty her attack is before sending his Blood Demon Art: Barren Hanging Garden at her, which she barely fends off with the Flower Breathing, Second Form: Honorable Shadow Plum. Doma notices that she is only able to counter and dodge his attacks because of her sharp eyes, since she takes note of the subtle movements of his shoulders, gaze, toes, elbows and knees to predict what he'll do next, and decides it's best to prevent this by taking her eyes out with a swing of his fans. Kanao dodges, and charges at him with Flower Breathing, Sixth Form: Whirling Peach which is nullified by Doma's next Blood Demon Art: Freezing Clouds. The Upper Rank sends two more attacks, Lotus Vines and Cold White Princesses, her way, which she only just avoids before his Wintry Icicles begin to rain on her from above.
Kanao dodges again, moving farther away from the Demon, who laughs at her and says that she can't keep moving backwards if she wants to cut off his head. At a speed too quick for the eye to process, Doma runs at Kanao and snatches her blade, returning and planting it in the ground a distance away from her. He says she better come and get it quickly if she wants to surviveagainst him, before sending his Scattering Lotuses at the Demon Slayer.
At that moment, Inosuke breaks through the ceiling of the room, protecting Kanao from Doma's attack with his Beast Breathing, Fifth Fang: Crazy Cutting. He looks at Doma's eyes and notices that he's Upper Rank Two, which he screams out, happily shouting that if he beats the Demon he'll become a Hashira and asking Kanao what his Hashira title should be. Inosuke notices Kanao's injuries and asks what happened, saying that Shinobu would be mad if she found out she was injured, and Doma explains that Shinobu is dead because he has absorbed her. Enraged, Inosuke rushes towards the Upper Rank with his Beast Breathing, Fourth Fang: Slice 'n' Dice.
Kanao shouts out a warning to him not to breathe in Doma's cold air as the Demon remarks on how messed-up his technique is. Doma attempts to slice off Inosuke's head with one of his fans, but the Demon Slayer flips away from him, launching himself from the flat edge of the fan and landing next to Kanao. He hands her her blade, which he had taken back from Doma, and tells her never to let go of it again. Doma smiles and compliments Inosuke's speed as he jumps towards him, and the two swiftly engage in quick combat, launching Breathing Styles and Blood Demon Arts at each other at alarming rates.
Inosuke kicks Doma in the stomach, sending him skidding backwards as he dislocates the joints in his right arm and prepares to swing his sword at the Upper Rank's neck. He misjudges his swing and instead slices through Doma's eyes with his Beast Breathing, Ninth Fang: Extending Bendy Slash, and the Demon laughs at his unusual technique as his joints relocate.
"I'll create Hell for you!"
Doma calls Inosuke messed-up and says that he's never met a kid like him before despite his long lifespan, to which the Demon Slayer replies that that's obvious, since he is the great Inosuke. At an incredible speed, Doma lurches forward and snatches his mask from his head as he's speaking, and Inosuke, enraged, yells at him to give it back. The Demon notices his face, and says he remembers Inosuke from somewhere, asking him if they'd met before. Inosuke denies this, but Doma remembers his interactions with Kotoha Hashibira, Inosuke's mother, and, after evading a Beast Breathing, Sixth Fang: Palisade Bite attack from Inosuke by slashing his chest, explains to her son that he killed her. Doma calls Kotoha stupid and unfortunate, saying that there wasn't a happy moment in her life, and Inosuke, having remembered this story and now enraged, thanks Doma for allowing him to remember this story and promises to not only to kill him for what he did to Kotoha and Shinobu, but to put him through hell beforehand.
The Demon sends his Blood Demon Art: Freezing Clouds at Inosuke, which he blows away with Beast Breathing, Tenth Fang: Whirling Fangs as Kanao prepares to use another Flower Breathing Form to attack him from behind. Doma bats her away with one of his fans and moves away, and Inosuke yells at him to get back down so they can continue fighting. He replies that he can't, since Akaza has been defeated and he doesn't have time to play anymore, and uses his Blood Demon Art: Crystalline Divine Child to create smaller clones of himself for Inosuke and Kanao to fight instead. The clones attack the Demon Slayer duo with Doma's techniques as the real Doma starts to walk away, the clones using his Scattering Lotuses, Frozen Lotus and Cold White Princesses attacks to hold the duo back. Now at the exit, Doma decides to create three more clones to let loose around the castle in order to kill the rest of the Demon Slayers there, and overhears Kanao shouting to Inosuke that they have to hold their ground just a little longer against the crystal children. He wonders what this could mean, but then dismisses it and begins to reach for the door handle.
Suddenly, Doma's face begins to melt. He drops to the floor, one of his arms snapping off, and his crystal children begin to crack and disintegrate as he wonders what's happening. Inosuke asks if it's a trap but Kanao, having been informed prior to the battle of Shinobu's plan to kill Doma, tells him that it isn't, and that the Demon is being melted by the poison Shinobu had in her body when he consumed her. She tells Inosuke to aim for his neck to finish him off, and, in a panic, Doma plays his final and most powerful card, Blood Demon Art: Rime - Water Lily Bodhisattva.
Doma's ice Bodhisattva statue slams down its hand on the floor of the room, creating a small earthquake that sends Inosuke and Kanao up into the air. Kanao notes that his technique lacks precision, and was clearly the Demon's last effort to protect himself with the little energy he had left, deciding to use Flower Breathing, Final Form: Equinoctial Vermilion Eye to try and break through him. Doma's statue grabs Inosuke in one of its hands as Kanao leaps towards the Upper Rank, hitting her blade against his neck. She is unable to cut it because she got frozen, so Inosuke, on the spot, comes up with and uses Beast Breathing: Sudden Throwing Strike to hurl his blades at Kanao's to give it the extra strength needed to cut Doma's neck. They succeed in beheading him, and Upper Rank Two and his statue begin to disintegrate.
As his head falls to the floor, Doma thinks about how pathetic he must be to have lost to a poisoner like Shinobu, someone who didn't even have the strength to kill a Demon by cutting its head. He thinks to himself that he shouldn't give up, and that he should try and regenerate his head like Muzan can and Akaza almost did, but soon comes to realize that that would be futile, and that he is going to die. In his final moments, Doma says that he is not afraid of death or even frustrated that he lost, and recalls his past as a human and his inability to feel any emotion.