This is the first scan of the oni painting. Prior to this I sketched the original image and cleaned it up by tracing it on a light box, fixing messy lines and altering proportions where necessary.
I start laying done initial tone and shade with a water proof black ink. I also fill in any flat black areas using the same ink.
I add color using water colors, building tone and depth gradually.
Here is where I add the finished painting. Color, more gray wash, and a coffee wash in the back ground. The photo is a little distorted due to curling, and the lighting is terrible despite photoshop corrections, but the result is decent enough.