During the presentation of Lightning Returns: Final Fantasy XIII there was an oil painting by Art Director Isamu Kamikokuryo on display, portraying Lightning herself.
Today Square Enix published a video that shows Kamikokuryo-sensei as he works on the piece of art. We also get to catch a glimpse on the studio and the tools he used.
While it's not exactly gameplay, it's a very interesting window on the work that gets done much before we see a game actually taking shape. You can enjoy the video below.
http://www.youtube.com/embed/dRXhos7Pxxw