Pretend Family

Tanjiro collapses from his wounds and crawls towards Nezuko, who has fallen and isn't moving. He smells blood behind him and realizes he normally smells ash when demons were killed by his sword. Rui stands and puts his head back on. He tells Tanjiro he cut his neck with one of his own threads when he realized he would be decapitated by the nichirin sword, which would have killed him. Enraged, he encircles Tanjiro with threads to mince him, only for Giyū to arrive and save him. Giyū congratulates Tanjiro on holding out until he arrived. Rui throws a sheet of threads at Giyū, who uses Water Breathing's eleventh form (there are only ten officially) to shred them when they reach him. Giyū then beheads him. As the Daughter runs, she remembers when she was being chased by Demon Hunters and saved by Rui, promising to join his family. Rui fed her some of his blood, giving her her current appearance. There were many siblings Rui had shared his blood with and he insisted they pretend to be a family. If they did something Rui didn't like he'd punish them, sometimes by wounding them, other times stringing them up and letting the sunlight kill them. Thus the numbers decreased to five. The Daughter comes across Murata and ensnares him in a cocoon filled with acid that will liquefy him, only to be knocked to the ground by Shinobu. Shinobu asks her how many people she's killed, saying (smiling all the while) that once she tortures her appropriately for all the people she's killed (gouge out her eyes, rip out her organs, ect.), they can be friends and her sins will be forgiven. The Daughter refuses so Shinobu uses her Insect Breathing to approach and cut her neck with her sword. Shinobu's sword is sharp only at the tip as she lacks the strength to behead demons. However, Daughter dies seconds later from the wisteria-based poison Shinobu invented and coated her sword with. Shinobu then frees Murata. Tanjiro makes it to Nezuko and drapes himself over her body protectively. As Rui dies, he thinks he made the pretend family because he had no memories of when he was human, and he thought if he could feel a familial bond, his memories would come back. He looks upon Tanjiro and Nezuko, wishing he had what they had.