A witch who resides within Eva's heart. She represents all of Eva's dark desires from her childhood, including her greed for the Ushiromiya family inheritance; as such, she has the appearance of Eva as a young girl.

She first appears in Banquet of the Golden Witch, where she helps Eva solve the riddle of Beatrice's epitaph, leading to her discovery of Kinzo's hidden gold and her inheritance of the Ushiromiya family. As stipulated in the epitaph, Eva inherits the name "Beatrice" and is granted the titles of Golden and Endless Witch, with Lambdadelta as her guardian. Eva-Beatrice is described by Ange as a "black witch," meaning she manipulates others through anger and hatred. In many ways, she is even crueler than the original Beatrice, using her Endless Magic to "play" with her victims by killing them in bizarre ways (drowning in a sea of jelly, crushing under a mountain of cake) before resurrecting them and killing them again, repeating the cycle until she tires.

She is most likely the manifestation of all the Eva culprit theories similar to how Black Battler is the manifestation of all the Battler Culprit theories.

She is very mocking of others, repeatedly taunting them by saying, "Heso demo kande shinjaebā?" (ヘソでも噛んで死んじゃえばぁ??, lit. "Why don't you bite at your belly button and die?").