Ruri "Rui"

Demon from distant world.
First princess, and rightful heir to the demon kingdom.
Her real name is Ruri. 
She hates that name, so she decided to change it to Rui.

She wants to kill her younger sister, Loki.
To achieve this, she allied herself with Curo and Akatsuki.

"Dont worry, I'll kill you nice and slowly..... by twisting your rotten bones in every direction !"