|Alias||Lilith, The World's Strongest Nightmare|
|Previous Affiliation||Kusuki Erize|
|Base of Operations||Itogami Island|
|Anime Debut||II Episode 1|
|Novel Debut||Volume IX - Black Sword Shaman|
|Japanese Voice||Nao Touyama|
Yume Eguchi (江口 結瞳, Eguchi Yume) First appeared In Volume 9, she was the key to awaken the Leviathan. She took a liking to Kojou and seriously dreams of marrying him.
Yume appears to have a body of a 10 year old (Approximately). She has short purple hair that ends with a small tilt and reaches her shoulders. She is seemingly always wearing a black headband with two ribbon-shaped symbols on each side and also has Light Blue eyes. When Lilith, the Succubus residing within her takes over her body, she grows a dark purple tail that ends with a reversed heart-shaped symbol, and when needed, a pair of wings that have the same color as her tail, but with purple horns at the top.
She is the vessel of Lilith, the world's strongest succubus.The bullying Yume had gone through because of her mind-control magic made her think that her existence will always cause problems and harm to others, and she could not kill herself in a simple way because Lilith would simply find another suitable vessel and that person would also have to suffer. So she decided to assist Taishikyoku in their plan to control Leviathan, the strongest living weapon from the ages of the gods as she is the being with the strongest mind-control magic, only to betray them and reveal her true goal which was to die inside Leviathan, which has the ability to dissipate any entity into nothing and which will kill her along with Lilith.
Black Sword ShamanEdit
Mind Control: Succubus or "Mumas" are know to be able to control people's minds by making their deepest desires go berserk. And Yume, who is the vessel of the World's Strongest Succubus has an exceptionally strong mind-control magic which can even control legendary creatures.
Pacification: This can also count as a mind controlling ability, whereas Yume/Lilith starts humming a certain melody which activates a mind control magic strong enough to pacify Leviathan, a living weapon from the age of the Gods. This Ability has been known to generate a strong yellow light from the user's body.