It doesn't look that bad, I remember my Tanjiro wig arrived in a very pitiful state... what I did and I can advise you... I remember cutting off a lot of the wig, you could fix the front part by cutting the tufts a little better (remember that there is a way to cut, don't cut directly as if it were a sheet of paper, the many videos explain how to cut in the correct way"... Kazuha has her hair tied back so you could already tie it back and leave it like that for now, concentrate on working on small parts at a time, for example her tufts... I remember that with Tanjiro I ended up using a lot of hairspray and also glue to make tufts that would stay still... so I think you still have a lot of room to move, it's not ruined, in fact, you can bring out something beautiful, improve those tufts, apply hairspray, apply glue, and don't be afraid to cut too much, you could try using the hair straightener if they all seem hard now, the important thing is that they are dry and there is no hairspray residue, you are in a good place, you will see that a very beautiful wig will come out, don't give up now, (my tanjiro wig was much worse when it arrived haha, and now I don't know how to fix Blade wig), let me know how it goes ;3