Hello!
I read the first (and only) chapter of Mr.Devil, and I have to say I see two issues with it that you need to address.
Firstly, there's the language. It appears to me that English is not your native language. That's fine, too - you have very few spelling errors, for one. You need to proofread more, root out all the grammatical errors, and odd turns of phrase.
The second issue is the formulaic plot - the pretty girl, the "average" protagonist, the bully. Does it seem very original to you? That will be more difficult to ammend. If you choose to continue this, it has to be the very best, in order to rise from among a large number of very similar stories.
Keep writing, though! No other way to get better at it.