Yumiko is a timid, quiet nun with Multiple Personality Disorder who is a pacifist and is easily frightened and acting in a cute timid manner. However, when her glasses come off, her alter-ego, Yumie, is unleashed. Yumie is impulsive and violent, showing no fear of anything and preferring to negotiate using the sharp end of her katana. She seems to genuinely enjoy killing people, having almost superhuman strength: she is adept enough to kill her victim from outside the room, and is capable of smashing heads into walls with her bare hands. Yumiko has often commented how hard it is for her to "get Yumie to sleep" after she has been provoked into action. Her raw strength, fearlessness and fearsome katana skills make her the ideal partner to Heinkel, who is cool-headed and analytical. Both Yumiko and Yumie are devout to their religion; however, Yumie is loyal to her church to the point of fanaticism, and is glad to slice down anyone she sees as a "heathen".