Jack-O' is one of the three servants of That Man, alongside Raven and I-No. Her past is shrouded in mystery, and her own memories are vague. Due to being awakened in an incomplete state her memories and personality data are fragmented and unstable. This instability has resulted in the side-effect of a split personality of sorts: That of a cool and collected adult woman, and a child-like one that is playful and cheerful, with her voice and mannerisms changing accordingly. As her awakening remains incomplete, she cannot function without her mask and candy.