Okay. This picture took me more time to finish than maybe it was worth. I literally went mad to decide where light should come from, and out of frustration opted for the easy way. I can't say I'm satisfied with it, but in the end I managed to finish it...

Genbu (Chinese Xuan Wu) is one of the Four Symbols of the Chinese constellations.
It is sometimes called the Black Warrior of the North, and it represents the north and the winter season. Although its name is often translated as Black Tortoise in English, it is usually depicted as both a tortoise and a snake, specifically with the snake coiling around the tortoise. (thanks to Wikipedia for the explanation here [link] ).

In a fantasy chinese-inspired setting I'm creating, the Xuán Wǔ is one of the great four fiefs of the empire, and it's famous for his well disciplined army and the exceptional weapons and armors it produces thanks to the abundance of metals that can be found in its mountains.
Well, what to say, despite the roughness I hope you like it...

Edit: added some more contrast on her face and darkened the Xuán 玄 character on the left banner.