hahaer almost 11 years ago I heard the gray haired girl was going to be the last boss for Hisoutensoku, but I'm not sure if it's confirmed or not since I can't read moonrunes. She appears in this pixiv post: http://www.pixiv.net/member_illust.php?mode=medium&illust_id=5343744
Delta Wave almost 11 years ago "Gakutensoku Sen"Surmane is sure, I think. But her personalname "Sen" may read different way.