An aquatic demon with a humanoid figure and sleek, angular features, displaying a striking blue skin tone. Its brow is furrowed in a perpetual scowl, and its mouth gapes open to reveal rows of sharp teeth. The creature is set against an ethereal underwater background, its form illuminated by the dramatic and immersive cinematic lighting typical of Unreal Engine 4. The overall scene captures a blend of eerie elegance and otherworldly menace, as if the demon is both a guardian and a predator of its aquatic realm.