AidaHanabi The idea is great, the way you wrote during the first 2 chapters are amazing but why am I seeing simple mistakes? We are talking about grammar, a mixture of UK and US English and several small mistakes with the adjectives used. Most the things have been mentioned above except one small thing which I would like to mention here, the usage of caps such as the prologue usage of (ex. "YUKIII") this needs to be removed because it affects your novel quality.
For the adjectives, I would recommend to Try to find words or specific adjectives that capture what exactly you are trying to say instead of using two-word phrases with modifiers like "very" to hold up weak adjectives. (EX: very hard)
I can see some improvements from chapter 1-10 and some changes to your writing which means you have improved either from help or by self-reflection on mistakes (Both are good). Hopefully, you can improve the main things I have pointed out, I am not a professional but a reader and this small things are easy to spot when you are reading carefully. Good Luck and keep up the good work.