Derieri is an elite warrior of the Demon Clan, serving directly under the Demon King as the Purity of the Ten Commandments. Derieri is a toned woman with long spiky orange hair. She wears no clothes, instead covering the breasts, left arm and right leg in her own darkness. She has demon markings on her left cheek which resemble a beast's open mouth with a circle in the center. Derieri lost her left arm in a fight with Sariel 3000 years ago and now uses her darkness to create one in its place. Currently, after her battle with Nerobasta, her hair becomes significantly shorter and more tomboyish, mimicking her appearance 3000 years ago with the original Ten Commandments. After defecting from the battle to conquer Britannia, Derieri temporary wore a black skirt and long sleeve open collar sweater with black boots. Derieri has a laid back and nonchalant demeanor. She is usually calm and does not seem to be shocked by many events. She expresses laziness and boredom the majority of the time. Though, Derieri has a very quick temper when certain buttons are pushed, such as her sister's death and when facing Meliodas. She has a very strange way of speaking, usually prefacing her comments with "To say from the ass" or "Taking it from the ass". Which roughly means "long story short", "in other words" or "by the looks of it". She harbors a great hatred towards the Goddess Clan , due to a situation where they broke a treaty and slaughtered her sister and many demon prisoners of war, and seeing one is one of the few things to change her normally apathetic demeanor. Going by her reaction to Elizabeth Liones she seems to especially hate Elizabeth, most likely for her role in her sister's death. It was established that Derieri was once a different woman in the past. Monspeet stated that Derieri talked much more and was very open, but after her sister died she turned silent and taciturn. After being treated by a human woman when she and Monspeet fell into her house by Meliodas' Full Counter, Derieri seems to develop a fondness for humans as she and Monspeet killed a bear causing disasters for the human's farmland while withdrawing from the battle and conquest of Britannia. She was visibly upset and hurt when Estarossa killed the farmland girl who sheltered them and tried avenging her after she was killed. As it turns out, the farmland girl had earlier "saved" both Monspeet and Derieri. Derieri is able to show remorse for a human that had tended to them. During her time with the humans and contemplating her past, Derieri has grown conflicted with her long-held convictions towards humans and goddesses, along with her loyalty to the Demon Clan. Derieri has eventually become more open and talkative like she used to be.