Heard about
Adobe's content aware fill? Jealous?
No need to be! GIMP has a nifty plug-in very similar that's available for free! It's called Resynthesizer and you can download it
here, at it's official website.
I recommend downloading the "Compiled Windows version: resynthesizer-for-Windows-0.13b.zip". It's the .exe version and easy to install. Or maybe I'm technotarded and need stuff to install itself. Whateva!
Anywho! Open your picture in GIMP.
I will be using this for the example.
Whaaat! Sailor Moon!? YES. DEAL WITH IT.
Next step is to lasso, using the Free Select Tool, a loose selection around the part you want removed. I lassoed around Kunzite and Zoisite.
Right click on your selection, scroll down until you find Script-Fu > Enhance > Smart Remove Selection.
A small box will pop up, asking what radius you want to select from. I used "600" this particular time. When you feel satisfied with your number, hit OK.
Viola!
Yeah, it could still use a little clean up, but it's pretty nice if I do say so myself.
Have another example!
BEFORE:
AFTER: