Outwardly, he is carefree, confident with a lazy smile or smirk, he enjoys provoking people and giving offhand compliments. He can be condescending, and somewhat selfish at times. Osamu (Atsumu’s twin brother) has described him as someone who doesn't listen to others, doesn't return what he borrows, and lies habitually. Atsumu is a competitive person who hates losing and a perfectionist who has ridiculously high standards for himself. His hair is blond and a dark undercut, he has brown eyes.