Despite his flirtatious nature (he is quite famous amongst female students, much to Tanaka and Nishinoya's envy) and childishness (as pointed out by his nephew and Iwaizumi), Oikawa is an excellent, well-rounded player and is extremely serious about volleyball. He's known to have a "disgusting personality" amongst both opponents and his own teammates because of his smug attitude. 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 (Oikawa indignantly responds by asking why he would do that to his own teammates).