Nezuko emerges from her box to viciously attack the tripartite demons, but when Tanjirou tells her to cease her attack, she dutifully returns to his side. He has her protect Kazumi and the young woman he rescued while he dives into the soupy bog where the demons dwell and devour.
While the demons are confident of their aquatic home-field advantage, the because Tanjirou trained in the thin air of the mountains and his attacks are water-based, he has no trouble executing a devastating whirlpool attack that chops the two demons into rustic chunks.
He returns to the surface just in time to stop the third and final demon from further harming Nezuko, who’d already received a nasty slash to the forehead. Before dispatching him, Tanjirou asks about Kibutsuji Muzan, but the demon start to smell strongly of fear—a fear so intense he literally can’t say anything about Kibutsuji.
While Tanjirou was able to defeat the demon and save one of the women, that woman wasn’t Kazumi’s fiancée. Tanjirou tries to comfort him by saying he must keep living despite life’s devastating blows. Kazumi lashes out in anger—how could a boy know what he’s feeling? But Tanjirou gently takes Kazumi’s hands in his and smiles a gentle smile, and Kazumi realizes Tanjirou knows all too well, and his hands aren’t those of a boy.
A Demon Slayer is always in high demand, so within moments of completing his first official assignment, his crow arrives with his second. He and Nezuko travel to Asakusa, Tokyo, and he is immediately overwhelmed by the densely packed humanity and the lights that make it as bright as midday.
Since this is the Taisho period, electricity is commonplace in the capital and there’s a vibrant streetcar network; we don’t see any cars buzzing around, but only because they’re still pretty rare. The huge city looks and sounds fantastic, and seems to pulsate with a modern energy Tanjirou has never before encountered.
Tanjirou is only one slurp into some therapeutic udon when he detects a scent that quickens his pulse and has him leaving the sleeping Nezuko at the stand. He dives into the crush of Tokyoites, following the very same evil scent that was present when his family was murdered, and it leads him to a fair-skinned man in a western black suit, a white hat, and reddish eyes.
This is it: this is Kibutsuji Muzan, the progenitor of all demons whom Tanjirou has been seeking. It’s almost too tidy that he’d locate someone so reluctant to be found he threatened other demons not to talk about him, but then again maybe he simply doesn’t consider Tanjirou a threat and would just as soon dispatch him.
As for Tanjirou, before he can unsheathe his sword, Kibutsuji makes a quarter-turn to reveal he’s holding a young human girl, his daughter. Soon, his wife appears, wondering who the boy in the checked coat is. To the mother and daughter, Kibutsuji is their husband and daddy. To Tanjirou, they’re his hostages. But that’s only the beginning: Kibutsuji quickly slashes a passing man without his wife or daughter noticing.
That man instantly transforms into a demon and bites his wife, starting a panic in the chaos of which Kibutsuji will no doubt slip away while Tanjirou tries to clean up the mess. Perhaps this was just a matter of Kibutsuji’s guard being down, in which case he won’t be so careless next time.