Nagumo is a handsome man of tall and slim build, medium-length black hair and large black eyes. He wears a red polo shirt with teal, black and white triangle-shaped patterns under a cream-colored trench coat (in the manga, the shirt is white with patterns being red and navy blue, while the shirt being light blue and the coat is brown in the digital-colored manga) as well navy-blue pants (black in the digital-colored manga) and black shoes.

He occasionally wears a white buttoned shirt with a black tie under a dark green business suit (in which he sometimes omits the suit and tie) He also carries a gray briefcase around on his back, which in it contains his signature weapon.