Mostly a clean and good looking skin apart from some things.
Some elements look a bit jagged (at least on 1080p), for example, defaults or hit50/100/300. While playing a map the upper right corner section containing score and map progress looks a bit cramped; if one is using the default progression it hugs the score numbers since the score files don't have enough empty space beneath them. Leaving some empty space both beneath and above the numbers will make it look better. ScoreOverlap could maybe also be changed a bit to allow a little more spacing between the numbers. Setting AnimationFramerate to 4 in skin.ini makes followpoints look glitchy, so you can just remove that from skin.ini or modify the followpoints as well. Sliderfollowcircle's ring's blur crashes with the edges of the image making it look crappy
https://puu.sh/xn1p4/c38221679b.png . You should be able to fix this by making the whole circle a bit smaller or keeping the circle the same size but increasing the image's dimensions. Menu-background has to be in jpg format instead of png for it to work. Score v2 mod icon could be skinned. Lastly, you have some unnecessary hitsound elements in the folder which are not used by the game (numbers or extra letters in the names e.g. normal-hitclap2).
Gameplay isn't anything new but it works which is the most important thing about it. I really like the menu-button-background and all the anime elements; cute girls are always a plus
. Sorry for this amount of criticism but it's only to help you improve!