Seraph Eden is the leader of the few surviving angels in the Monster World.
(The following is based on a simplified translation and may be changed later)
After Ilias and her army were defeated in the Monster World, many of the angels managed to survive to the present day, though some were captured and became slaves or experimental subjects for the monsters. Eden leads a band of rebel angels to liberate their captured brethren. She has attacked the monsters countless times, but with no lasting results. However, her persistence in the face of overwhelming odds could be said to be a testament to her leadership ability and the strength of the rebels.
She's currently targeted by Hiruko, who wishes for nothing more than devouring the life of the seraph.