The captain and setter of the Aoba Jousai High School Volleyball Club. Oikawa was also Kageyama's senpai when they were attending Kitagawa Daiichi. According to Kageyama, he is a very talented setter and volleyball player with a bad personality.
Oikawa also frequently makes cheerful remarks, but follows them up with serious or intimidating afterthoughts. Despite his flirtatious and blasé exterior, Oikawa is extremely intelligent and cunning, to the point of his own teammates stating they wouldn't want to be friends with him because he figures out everyone's weakness.
He holds a grudge against Kageyama, whom he mockingly calls Tobio-chan. This is due to his feelings of inferiority when compared to Kageyama, who has been hailed as a genius setter since their time spent at Kitagawa Daiichi. Kageyama can unintentionally bring out the more childish or rash aspects of Oikawa's personality.
(Source: Haikyuu!! Wiki)
