kind of cute, huge potential
I didn't mind the audio quality -too- much, considering you put subtitles. There was only one grammatically awkward part, so your English really isn't terrible at all.
As for the voices, the demon's voice annoyed me. It's my own personal preference, but I just didn't like it. In general, you were almost monotonous with the voice acting. You could liven things up. Even if you're "depressed", try not to make it sound like you're reading a script.
There were no spelling errors I noticed, which is a huge bonus.
Your artwork was cute. I assume you're using a tablet. There's not a lot of movement though, in regards to animation. It's very static.
The story itself is a little too childish in my opinion. I'm not saying that loneliness is something people should get over, but because you dropped us off into the story, there was no real emotional connection to the demon. It needs more details, more background, more dialogue.
All in all, for your 3rd/4th flash animation, this was a great job. If I may suggest, since English isn't your first language, you can always try speaking in your native language, with subtitles. This can also give you more characters, if trying to change your voice hurts.