Standing 182cm or 5'10", Nakao is the same height as his friend Ryoji Suzuki. He has a medium-muscular build and always wears his hair in a bedhead-type style. Nakao doesn't have much style compared to others as he's usually just seen wearing t-shirts, hoodies, and khaki pants. Occasionally Nakao is seen wearing a pair of thick framed glasses.
In the anime, Nakao has brown hair and brown eyes. During warmer weather, Nakao's uniform consists of an unbuttoned short-sleeved white dress shirt with a red star on the chest, an orange t-shirt underneath, gray pants, and brown shoes. In the winter, he wears the same uniform but the dress shirt is buttoned up with an unbuttoned peach cardigan that has red stripes on the arms, red buttons, and a red star on the chest.
In the manga, he reddish-brown hair and matching eyes. Although Nakao occasionally wears his school uniform during important school events, he is typically seen in casual clothes.