Arachne is actually Kurai's older sibling and was told that she was heir to the throne. When Gehenna was attacked and destroyed, she discovers that she was only a decoy to protect the true heir, Kurai. She initially despises her and sells her own soul to Lucifer through the Mad Hatter, who seals a spider demon in her chest. She then poses as her cousin to get close to her and kill her, but grows to genuinely care for her. She is responsible for Boyz's death when Boyz finds out who Arachne really is. She sacrifices herself to be the 999th bride of The Demon Lord to save Kurai. Arachne almost always dresses 'as a woman' and refers to herself as 'one of God's mistakes', a woman trapped in a man's body.
