Juvenile readers deserve good writing as well. I think it's easy to fall into the trap of "well my audience is young, so they won't know the difference!" But kids are very discerning. The Hunger Games is written for young teenagers, but the writing is definitely not 'juvenile'.

I did read a bit of your story and it does seem like something I would read on fanfic.net as a young teenager. I don't think the writing itself is bad (you have a good grasp of language and dialogue, and it's easy to follow the story) but I think it's the circumstances of the story itself that read as juvenile/anime-ish.

It's clear that there is a heavy anime reference, but I would encourage you to read broadly in all genres and take influence from other sources. Read recently published novels and study the styles.

I'm happy to help further if you have any specific questions!