TV-Series
Description
Ennea is a central character in the Demonbane series, whose outward appearance as a gentle and domestic girl belies her true identity as one of the most powerful and tragic figures in the narrative. She is introduced as a mysterious young girl found by the protagonist Kurou Daijuuji and his grimoire partner Al Azif during a rainstorm, seemingly with no memory beyond her name. In this guise, Ennea is a quiet and unassuming presence, with a cat-like demeanor. She displays an incredible aptitude for housework, particularly cooking, at which she is a professional-level expert. This immediately creates a stark contrast with the helpless Al Azif, who is famously incapable of such tasks, and Ennea's sweet and attentive nature leads her to become deeply attached to Kurou, often trying to win his affection. Despite her demure facade, moments of a more knowing and unsettling maturity occasionally slip through, hinting at the ancient and dangerous being hiding beneath the surface.

This gentle girl is a false identity. Ennea is, in truth, the fearsome sorcerer known as Nero, also called the Tyrant, who is considered the most powerful member of the antagonistic organization Black Lodge's inner circle, the Anti-Cross. Her power is said to rival that of Master Therion, the leader of Black Lodge, and she is so dangerous that even her own allies kept her bound and confined. Her designation is number nine, as Ennea is the Greek word for the number nine, a reference that connects her to Kurou's name, which contains the character for nine, and her development number as a Moonchild. She was created as a "Shaman of C" under the Moonchild Plan, intended to serve as a priestess to activate the god-like being Cthulhu. Her true form as Nero is that of a violent and ruthless figure, having a history of killing Kurou, Master Therion, and even destroying the titular robot Demonbane in previous cycles of existence.

Ennea's primary motivation is a desperate and all-consuming desire to escape the "infinite spiral," a cycle of reincarnation and repetition that traps her and the other characters in an endless loop of suffering and death. Throughout countless iterations of reality, she has been forced to play out a role that inevitably leads to her own death, often at the hands of those she has come to care for, to serve the resurrection of Master Therion. Her entire scheme in assuming the identity of Ennea and attaching herself to Kurou is a calculated part of a grand plan to break this cycle. She manipulates events so that Kurou will ultimately destroy her using the Shining Trapezohedron, a reality-warping super-weapon, believing that its power of causality collapse can erase her so completely that she will not be reborn again. This makes her a uniquely tragic antagonist, as her villainous acts are driven not by malice but by a profound longing for a final, permanent end to her agony.

Her key relationships are complex. Her primary connection is with Kurou Daijuuji, whom she genuinely comes to care for during her time as Ennea, acting as a devoted companion to him. However, her true goal as Nero is to engineer a confrontation where he kills her, creating a deep irony in their bond. She also has a tense and competitive relationship with Al Azif, who senses that Ennea is not an ordinary human and is fiercely jealous of Ennea's domestic skills and her closeness to Kurou. Her relationship with Master Therion is that of a powerful subordinate who is also a threat; he created her or selected her for her purpose, but also had to personally restrain her when her power became too uncontrollable. She is deeply connected to the cosmic entity Nyarlathotep, who chose her for the role of mother to Master Therion's ultimate form and who seems to observe her struggle with amusement.

Ennea's narrative development is one of a tragic figure seeking liberation from an eternal, cruel fate. In most iterations of the story, her plan ultimately fails. When Kurou is forced to confront her, his compassion prevents him from becoming the cold, detached entity needed to wield the Shining Trapezohedron as a pure instrument of erasure, and her death becomes just another in the long line of tragedies. In the visual novel's Al Azif route, she experiences a form of release, watching over Kurou and Al from the shadows as they ascend to become Outer Gods in the "Old God Ending". In other stories, such as in the game "Kishin Hishou Demonbane," she finally confronts and forgives Master Therion before disappearing from the world. Her development is a constant struggle to turn a narrative of imposed victimhood into one of chosen sacrifice.

As a testament to her power, Ennea possesses several formidable abilities. Her magical grimoire is the "Nameless Sacrifice Book," and she pilots a colossal Deus Machina (a god-machine) over five hundred meters long known as the Nameless One. This machine wields a power known as "Denial," an ability that has the strength to defeat other powerful Deus Machina. Beyond her immense magical power as the sorcerer Nero, she also possesses combat skills that allow her to kill other powerful beings and even destroy Demonbane itself. Furthermore, as a Moonchild, she fulfills the role of a priestess capable of controlling the Great Old One Cthulhu, making her a key component of the grand "Plan C" for world domination. Her arsenal also originally included a magical gun, which, in a final twist of fate, Kurou would later use against her and other enemies.