this is my opinion
i have a right to it:
single dagger and twin rainbows look like they were squished.
kanji looks like a load of crap that has no artistic form whatsoever.
hazama yuki has no depth in his face, the shading in his hair looks like a ball and it looks like a poorly drawn toupee, his eyes are just not right, im sorry, but no good picture has triangular or square eyes, and the whole thing just looks...not right
sharingan user: there's a whole lot of pillow shading, again with the toupee..., the eyes nose and mouth are just a bunch of lines that you obviously didn't spend much time on, the ears aren't proporioned right, and the shading. oh the shading! you spent way too much time on that, and not enough on the important features!
hayakuretsu is the only thing that i relatively like
custom hollow mask...no ...just no...
and the rest of them... i think its all the same what i'm going to say
you need a LOT of work before any of this can really be presentable
go to these websites
i think you could pick up some things on basic drawing
https://tearain.tripod.com/hp/draw/draw.html
https://www.mangatutorials.com/
https://www.youtube.com/watch?v=FiQ3K6nyOek