A high-quality anime illustration depicts a majestic demon king, identified as Theresa from Arknights, standing alone in the center of an ancient, dimly lit castle interior. The scene is captured from a low angle, emphasizing her imposing stature. She has long, flowing purple hair and two prominent, long red horns curving from her forehead, with large bat-like wings extending from her back. Her light, casual attire consists of a simple dress with long sleeves, revealing her slender figure. She grips a massive great sword with both hands, holding it vertically in front of her, its blade resting on the stone floor. Her expression is calm and regal, with pink eyes gazing forward. The background features gothic architecture with stone pillars and arches, illuminated by soft, ambient lighting that casts dramatic shadows. The atmosphere is mystical and powerful, with a focus on detailed textures of the armor,wings, and fabric, rendered in a vibrant color palette dominated by purples and reds.
