Asta is a young man of short stature with an exceptionally muscular build. He has green eyes and messy, ash blond hair with a single strand protruding upwards from the center of his head. He keeps his hair together with a black headband, which has the gold-colored Black Bull insignia and has a red-colored four-pointed star with three stitches on the back of it.
Asta’s common outfit consists of a plain-white tunic with a V-shaped collar underneath a dark blue jacket whose sleeves extend only up to his elbows. He sports a pair of matching shorts which has a stitch marks on the left side. His pants also extends just below his knees. His shoes are made out of two different cloths, the parts covering his ankles, the soles the same color as his jacket and pants. The parts covering his toes are white, a vertical stitch mark going from the bridge to his toes.