Shizuru is happily washing herself, while Natsuki seems a bit worried about her new condition. 
Those characters are from Mai Otome, which is the "false" sequel of Mai Hime. Shizuru is the kind of good but evil character, and her smile is always dangerous.
So it happens often that you can imagine her doing some strange stuff to the others characters. In the anime, Shizuru and Natsuki are sharing a ambiguous relationship, so you can often see "yuri" fanart about those two. 
This drawing was done in the beginning of November 2007, after a friend was talking with me for a few months about a story he had in mind. He asked me if I could draw a few pics to illustrate it, so I did this first one and then waited that he could finish the story so I can read it and draw accordingly to it.
I'm still waiting to read it, and since he don't want people to read before he has finished, I don't know how it looks like.