In his half-demon form, known as "Black Asta," Asta's appearance becomes fierce and intense. His ash-blond hair turns jet black, growing spikier and more chaotic. His green eyes shift to a menacing red with slit-like pupils. A large, black bat-like wing emerges from his right shoulder, and his right arm is engulfed in dark, shadowy energy, forming claw-like fingers. Black markings spread across the right side of his face and chest, pulsating with anti-magic power. His usual outfit--black sleeveless shirt, dark jacket with gold trims, and baggy pants--takes on a more ominous tone, as if infused with dark energy. The Demon-Slayer Sword and Demon-Dweller Sword he wields become enveloped in this same black energy, making them even more formidable. Asta’s entire appearance exudes a fierce, battle-ready aura, making him a terrifyingly powerful force in this form. Picture Asta in a valley with dark light ultra hd quality --ar 1:1 --niji 6