100% Photoshop. Basically just sketchy lineart, watercolor brushes/textures, and a ton of layer blending. Lots of playing around, so it's a little too complicated to explain in a single comment. When I make another piece in this style I'll make sure to document the process for tutorial purposes c:
Link
Rinzy
These are absolutely fantastic! What program/tools are you using to achieve such a wonderful effect, if you don't mind sharing?