Tobio Kageyama (Japanese:
Kageyama's height and impressively sharp glare are said to be his most prominent physical characteristics. He is of a muscular build. He often emits an intimidating aura, which is heightened by the almost permanent scowl on his face. His black hair is cropped short, with a fringe that hangs just above his dark blue eyes. His typical attire consists of either his school uniform or practice clothes.
Perpetually sullen, arrogant, and undeniably short-tempered, Kageyama originally came off as a typical overbearing perfectionist, caring only about winning and completely disregarding the opinions and well-being of his teammates. His habit of complaining about their performance and barking orders at them eventually led the other players in Kitagawa Daiichi to nickname him the "King of the Court", a constant reminder of the oppressive, egocentric attitude he demonstrated during his volleyball career in junior high.
Unbeknownst to the majority of his schoolmates and acquaintances, however, he is actually much more sensitive and childish than he appears to be; he simply does not know how to control his frustration, and hence expresses his thoughts and emotions in an inappropriate way.
After everyone in Kitagawa Daiichi became fed up with him and abandoned his side, Kageyama was filled with genuine regret and developed an intense fear of being despised and mistrusted, but refused to openly discuss his problem until Tsukishima confronted him about it.
Despite his inability to properly socialize, he sincerely wishes to do his best and is extremely passionate and dedicated when it comes to volleyball, to the point where he gets overly excited about nearly every successful move he pulls off with Hinata.
Since joining Karasuno, he has grown to be more respectful of his upperclassmen (Sugawara and Asahi in particular), as well as more accepting of people whose abilities and/or views differ from his own (like Tsukishima), and has come to once again understand the importance of teamwork and mutual trust in the sport he treasures so much. Additionally, this has also helped him regain his confidence as a setter. He has also realized that he doesn't call the shots, and gives up control to Hinata and other spikers.
Kageyama is known as the "King of the Court" and a volleyball genius for his incredible technique and game sense. As a high-caliber setter, Kageyama has the potential to unify the team with his overwhelming talent, but he originally struggles with effectively communicating with his teammates. Over time, he has learned to utilize his skills to bring out the best of his spikers. He now pays attention to his spikers' condition and adjusts his toss accordingly instead of forcing them to match him all the time. 
In addition to his astounding accuracy and technical skills as a setter, Kageyama is a skilled all-rounder with a remarkable grasp of both the basics and the complexities of volleyball. He is capable of playing many other positions, including wing spiker, but chooses to become a setter due to his love for being the team's control tower. Kageyama also has an affinity for improvised strategy and is the first person to suggest using Hinata's prominent presence on the court as an effective decoy. Due to all these factors, Kageyama is one of the players selected to participate in the All-Japan Youth Intensive Training Camp.
Height and reach, as of mid-November:
- Fingertip Height: 239 cm
- Jumping Reach: 337 cm (spike) / 320 cm (block)
- Pinpoint Accuracy: Kageyama's most prominent and praised skill is his ability to accurately determine a ball's trajectory and tossing it to the exact point. Combined with the fact that he can set from any angle at incredible speeds, this makes his sets almost impossible for most of his opponents to predict and counter. His pinpoint accuracy is a necessary component in Kageyama and Hinata's infamous "Freak-Quick" sets. He can calculate Hinata's exact spike point to send the ball straight to him at the perfect moment in time. Moreover, Kageyama uses his accuracy and fast handling of the ball for other purposes too, such as straight shots and setter dumps.
- Minus-Tempo Quick Strike: Also known as the "God-Fast Spike", "Freak-Quick" or the "Oddball Combo", this is an offensive maneuver developed by Kageyama and Hinata during their three-on-three match against Tsukishima, Yamaguchi, and Daichi. It combines Kageyama's setting talents together with Hinata's speed, agility, and extraordinary jumping power. Kageyama uses his pinpoint accuracy in order to set the ball to Hinata's exact spike point. His toss is so accurate that Hinata can spike even with his eyes closed. Ever since the summer training camp, Kageyama has modified his toss to one that stops and falls around the spiker's hitting zone to give Hinata more control in mid-air. He also can send a toss close to the net for Hinata to spike it straight down.
- King's Toss: His best set is known as the "King's Toss," which causes the ball to go straight with a lot of force past through the spiker's point of impact. Originally, his teammates found this sort of set to be impossibly fast to spike. Following Karasuno's summer training camp, Kageyama learned to perform a set that falls around the spiker's point of impact by adding a backspin. The brutal force he'd habitually put into it would thus die out and allow the spiker to manipulate the ball in whatever way he wished.
- Jump Serve: Kageyama has a powerful jump serve that his opponents are wary of. Early on, he hasn't learned how to aim it yet, but during the Shiratorizawa match, he displays the ability to manipulate the power he puts into the serve in order to catch his opponents off guard (by dropping the serve shorter than expected, for example). By the time Karasuno reaches nationals, his jump serve has become a reliable weapon. He is seen scoring many service aces and even adding a side-spin to avoid the receivers.
- Dump Set: Kageyama often utilizes dump sets and almost never gets blocked. He's adept at finding the perfect moments to perform a dump set, often surprising both his opponents (such as Oikawa) and his own teammates. He can also fake this to set up a short-range quick attack.
- Two-setter Attack: Kageyama also has a sharp straight spike, which allows him to act as an extra wing spiker on the right side when Sugawara is used as a setter.
- One Person Time Difference Attack: Kageyama has shown the ability to match his spikers to perform a One Person Time Difference Attack. He utilizes this attack with Tsukishima, who delays jumping to throw off the blockers, during Karasuno's match against Shiratorizawa.
- Favorite Food: Pork curry with an egg on top.
- Current Concern: He gets the feeling that animals dislike him.
- Kageyama wears black volleyball shoes with and light grey accents.
- Since he was born in Japan and on the cusp if he was born before 11 am he is a Sagittarius; if he was born after 11 am he is a Capricorn.
- Kageyama usually buys a carton of milk or yogurt during lunch.
- He is the only first year on Karasuno's volleyball team that isn't a middle blocker.
- He's been playing volleyball since his second year at Akiyama Elementary.
- Kageyama is the youngest member of the team.
- He claims to have a poor memory when it comes to English vocabulary, but when he was quizzed by Daichi on tactic signals he was able to answer them quickly and revealed that it took him barely a day to memorize those. This shows that he does have a great memory, but lacks the motivation to put it to use on subjects that aren't related to volleyball.
- Kageyama has admitted to Hinata that he is jealous of Hinata's physical ability and reflexes. Specifically that Hinata has great ability but has not been able to hone it properly to his greatest potential. Kageyama says this is why he is 'irritated' by Hinata.
- Before choosing Karasuno, Kageyama tried to get into Shiratorizawa, but he failed the entrance exam. Afterward, he chose to attend Karasuno only because he wanted to train under the former Coach Ukai. However, Ukai collapsed shortly before Kageyama joined.
- In the One Shot, Kageyama's reason for joining Karasuno was that he wanted to fight "Top Schools". Hinata and Kageyama had also formed their "Freak-Quick-attack.” during a match against another school instead of during the 3-on-3 match.
- His birthday overlaps with the winter solstice (December 22nd, the shortest day and longest night of the year) which contrasts Hinata's birthday which occurs in summer solstice (June 21st, the longest day and shortest night of the year) respectively.
- His seiyuu, Ishikawa Kaito, is also the seiyuu for Nine, a character in the anime Zankyou no Terror. Number nine is Kageyama's uniform number.
- It has been hinted that Kageyama was the Vice-Captain of his Junior High Team, Kitagawa Daiichi.
- In Haikyū!!: One Shot, Kageyama's jersey number was 6.
- In the first popularity poll conducted by Weekly Shōnen Jump, Kageyama was ranked 1st. However, he was ranked 3rd in the second popularity poll.
- In regards to Kageyama's name, Furudate wrote, “I gave him this name with the image of “strong shadow” and “flying” in mind.”
- In an interview with Furudate about Kageyama's character, Furudate noted that they felt Kageyama turned out well.
- Hinata once called Kageyama "バテ山君" (Bateyama-kun), which translates to someone who is tired.
- Tobio (飛雄) - Flying Hero
- Kageyama (影山) - Shadow Mountain