A fused being, she is half Shakuyaku (human), and Kagan (golem). When they both came to terms with each other, they started calling themselves Shakugan.
Shakugan often looks like a human, but she can change her limbs to huge rock pillars at will.

She was a country girl that lived in poverty with her family, until she was discovered to have hidden powers and was thus sold by her parents to the monastery.