Tobio Kageyama (Japanese: 影山飛雄 Kageyama Tobio) is a first year at Karasuno High School; he is the regular setter of the Karasuno High Boys' Volleyball Club and plays a critical role as the deuteragonist of the Haikyū!! series. Initially, he was referred to as the "King of the Court," a derogatory nickname that insinuates his autocratic nature, given to him by his former teammates at Kitagawa Daiichi during his late junior high school days. Kageyama is also widely regarded as a stunning prodigy and an absolute genius by many of the prefecture's players and coaches. After joining Karasuno, he manages to change his attitude for the better with the help of his new teammates and 'rediscover' what it means to be a part of a team. Currently, he has been chosen to train at the all Japan youth training camp and there's a strong possibility that he will become part of Japan's national volleyball team in the future.

Kageyama's most prominent and praised skill is his ability to accurately determine a ball's trajectory before he sets it. Combined with the fact that he can set any ball from any angle at incredible speeds, this makes his sets almost impossible for most of his opponents to predict and/or counter.

As most blockers determine the spiker from the toss, it is a common misconception that it is Hinata's speed alone that makes the quick work. However, opponents are often left befuddled and confused when the ball seemingly disappears from sight, as Kageyama barely allows the ball to be cushioned against his fingers before he tosses it.

Kageyama uses his accuracy and fast handling of the ball for other purposes too, such as straight shots and setter dumps.

By observing Hinata's and calculating the height of his jump, Kageyama can figure out exactly where and when his partner will swing his hand in order to spike, and sends the ball straight to him at the perfect moment in time; this enables the duo to perform their infamous "Freak-Quick" sets.