Could this possibly be the first fan art submission to feature Rimuru? Hmm... that sounds like the title of an isekai.
I got into That Time I Got Reincarnated as a Slime just last year. I'm currently watching season 2. It's a very charming anime, I think.
This picture was mainly me playing around with Clip Studio Paint. I was mostly messing with transparency and blending modes. I actually like the result.
Done completely in Clip Studio Paint.