The artist said this monster girl is 延維/延维 (yán wéi) from The Classic of the Mountains and Seas. This twin human-headed serpent god was worshipped by an ancient tribe called the Miao.

有人曰苖民。有神焉，人首蛇身，長如轅，左右有首，衣紫衣，冠旃冠，名曰延維，人主得而饗食之，伯天下。

• Baidupedia"延维": http://baike.baidu.com/view/150813.htm