inkastarza
This story intertwines with the original story line. Back in the Sengoku period where Muzan and Yoriichi fight, He starts to feel some sort of "pity" towards the demon king, so he tells his right hand woman (Tamayo) to run off and never return, in which she correlates to by running off into the distance while Muzan Kibutsuji, the king of demons screams her name. There technically is no main character in this story, however, the plot focuses on Muzan, so he's can be considered the main character. Yoriichi is (sorta?) the antagonist, in Muzan's POV at least, but the plot in general is the same as demon slayer, just a more twisted turn. If you couldn't tell by the title, this stories' focal point is S&M, Sadism and Masochism.