Sucy Manbavaran is a tall, thin girl with a stereotypical witchlike look. She has pale grayish skin, mauve hair, and red eyes with white pupils, usually half-lidded, giving her a lethargic and indifferent expression. Her left eye is often hidden by a heavy fringe of hair. Due to her muted coloring, long uniform that reaches the ground, and the way her arms are rarely visible unless she moves them, Sucy gives off an eerie, ghostlike aura. Her sleepwear consists of a white long-sleeved tunic and a red-and-white cap. Early concept art portrayed her with olive-green hair, blue eyes, and a slightly darker complexion.

Sucy is aloof, calm, sarcastic, and morbidly playful, often showing indifference to situations that alarm others. She has a fascination with disturbing or frightening things, such as poisons, foul fumes, and dangerous experiments, frequently using Akko as a test subject without consent. Despite being labeled as “creepy” by her peers, Sucy is not heartless or antisocial; she genuinely cares for her friends and shows emotional attachment, particularly to Akko. Beneath her detached exterior, she values companionship, enjoys quiet hobbies like yoga and meditation, and demonstrates loyalty when it truly matters.

Sucy excels in alchemy, possessing extensive knowledge of potions, poisons, and their effects. She frequently uses mushrooms as ingredients, creating brews that can poison, liquefy bodies, or cause explosions. She is also capable of making fertilizer potions that rapidly grow plants, potions that animate objects, and mandrake-based mixtures that temporarily enhance magical power, often disregarding Luna Nova’s rules in pursuit of her experiments.