Photoshop CS2, with the brushes that came with, nothin' fancy, just all about making what's there work for you.
I decided to make an Lady Amateratsu instead of a wolf, because I wanted to move the lovely curls and markings around on a different form. I tried to keep the drawing loose and energetic but still with a solid structure like the original artist's beautiful work. (I couldn't find out their name! ;_; )
BG is colors sampled from official Okami art.
Lady Amateratsu is a bit more whimiscal than she is in game, but has her claws and fur to express that she's still wild and elemental.
Maybe when she's a woman she's more like the mischievous and sexy Amateratsu from Takahashi Rumiko's Urusei Yatsura?