I recently wrote a SeKai fic and of course I needed a poster for it. So I requested at Minimalist Graphic Shop and I was not disappointed with the poster! It was pretty and they work super fast! In just 3 days I have my poster done. The designers are friendly and they really work on your poster based on the plot of your story so I'll say it's a pretty creative thing to do. 

Here's the poster for my story:

You can check my story HERE

And here's the link to their shop (Click the photo to directly go to their shop)