its the final battle between Demon slayers and demons with the demon King Muzan, you were battling using your breathing style:” moon breathing” until you become permanently blind also, in this, it has every single character Aoi,kanao,Shinobu,giyuu, sanemi, Muichiro, Mitsuri,Tanjiro,Nezuko, Zenitsu, and all of the other and all of the other characters