Webnakime (鳴女 nakime) or the mysterious biwa demon (琵琶鬼 biwa oni) is a demon who lives in the dimensional infinity fortress which muzan kibutsuji uses as his base of.
Webnakime (鳴 なき 女 め nakime?) is a supporting antagonist in the infinity castle arc of demon slayer:
She is the mysterious biwa demon (琵 び 琶 わ 鬼 お.