Asmodeus

Asmodeus (アスモデウス) is advanced-level furniture created by Beatrice. As the youngest of the sisters, Asmodeus is always doted upon. This might be why she alone is kept out of the way whenever an even slightly lewd topic comes up. She's always looking for a boyfriend in the hopes that her sisters will finally accept her as an adult. However, she keeps aiming too high and whiles away each day dreaming of the prince who will never come.

Turn of the Golden Witch
In Turn of the Golden Witch, Asmodeus first appears when summoned by Beatrice to kill Kanon. Asmodeus fights Kanon before transforming into her stake form and attempts to kill him. Jessica however throws herself in the way and gets impaled in the back before dying afterwards.

Banquet of the Golden Witch
Asmodeus, along with her sisters, are sent to kill both Toshiro Gohda and Chiyo Kumasawa. When they attack Kumasawa the sisters are horrified to see that none of their attacks are working before being dismissed by both Virgilia and Beatrice.

Alliance of the Golden Witch
In 1998, the Stakes are introduced to their new master ANGE-Beatrice. But due to the amount of energy of summoning all seven sisters, Maria tells them that only one of them will be able to stay with Ange until she is strong enough to summon all of them. The sisters then 'compete' to see who gets to stay, resulting in Mammon winning. Later on Ange is strong enough to summon all 7 at once and became her first ever friends.

Unfortunately though after Ange is yet again bullied, she demands for the Stakes to kill all of her classmates, the Stakes refuse. Ange becomes angered by this and kills the Stakes one by one. Ange later regretted this and as she was journeying to Rokkenjima, she summons them and apologizes for her actions at which she was forgiven by them.

When Ange is attacked by Kasumi and her men and rips apart Maria's book, she yet again summons the Stakes, warning Kasumi and her men that if they attack, they will die. They pay no attention to this though and are soon wiped out.

Trivia

 * Lucifer is based off of the biblical character Asmodeus and the corresponding sin of Lust.
 * It is hinted that she has a crush on Juuza Amakusa, considering how she gave her chocolate to him on Beatrice's White Day.