Ayumi Tsuwabuki

Lady Mayumi's clone with the egg of next pixie king (the stolen treasure of the pixie's) infused with her so she aged faster than a normal clone that way at the earth users ceremony she could be sacrificed instead. Every 30 years the earth users must sacrifice one of their own to seal away a monster that their ancestors sealed away long ago at the cost of their most powerful casters life at the time. If the beast is released it will kill everything in its path, earth users view of life that is repeated by several different users is sacrifice. Rin fall's in love with her after listening to her sing at the end of episode 9 and tried to protect her from the other earth users that mistreat her and refer to her as property. Half-way through episode 10 you see how poorly they truly treat her when Mayumi's personal body guard/servant grabs her by her hair and repeatably slams her head into the ground. Rin end up freeing the beast and killing in order to stop the cycle of sacrifice and protect Mayumi and Ayumi, sadly he ends up needing Ayumi's help to defeat it and in the end he can not save her.