I notic that aaza is the only demon in the entire Demon Slayer story who does not have long nails and I think I know the reason when I saw this the first spot that came to my mind was that maybe it's because of Kaza retains most aspects of his human life like his fighting style tattoos and even his morals such as not consuming women all of which are linked to his past life but then I realized aaza fights with his fists and if he had long nails like the other demons he wouldn't be able to
close his fists properly unlike most other demons now this might just be my perspective but I think a caza's nails are long because of his fighting style and nothing else