First appearance December 12, 2005
Gender female
Species angel
Family Lucifer (uncle)

Cassiel: The niece of Lucifer. She and Rumisiel dated for 50 years, and she still seems a bit bitter. Her class nickname in the yearbook was "Bitch".[1]

She is an angel of the third circle, a master of disguise, and works for the fourth branch of the filing department, taking measurements on Earth and comparing them to the extrapolations the bureaucracy derives from the filing system, which may mean it's her job to catch the type of misfiles that Rumisiel caused involving Ash and Emily. Fortunately, she seems to be completely buying the Ash / Rumisiel dating story.

She has made several attempts to interfere, first trying to seduce Ash to convince Rumisiel that Ash was having a lesbian affair behind his back, then trying to influence James, and then trying to convince Rumisiel and his brother that something bad was going to happen to Ash unless they interfered with Ash's summer race. Fortunately, Rumisiel figured out at the last minute that there was no actual bad thing, she was just trying to trick him into interfering. She has disguised herself as a fellow student, a girl at the modeling party Ash went to (stealing another model's invitation and outfit), and as a catering assistant at Kate's wedding.

She seems unable or unwilling to reveal her powers publicly, and she seems scared of Rumisiel's brother Vashiel.

After Cassiel filed a report about Rumisiel's destruction of evidence, Xaphrael threatened her with death if she ever did such a thing again.[2]