Syusuke Fuji

Fuji is often seen with a calm and content expression on his face, with his eyes seemingly closed from lightly smiling. However, when he is excited or provoked, or when playing seriously, Fuji reveals his sharp eyes: they are blue in the anime and light brown in the manga.

Fuji differs from almost every other character in The Prince of Tennis in that he seems very relaxed and in control when his opponent is pushing himself to the limit, giving many the impression that Fuji is either a genius, who knows how to save his energy during plays, or that he does not really care about tennis itself. There are a few people that can "wake" the true player in Fuji and force him to play seriously, and these few are either nationally-ranked or extremely talented tennis players. Seigaku captain Kunimitsu Tezuka, Seigaku regular Ryoma Echizen, Shitenhouji captain Kuranosuke Shiraishi, and Rikkai Daigaku Fuzoku regular Masaharu Niou have been acknowledged by Fuji to be actual challenges.

Fuji has an older sister, Yumiko, and a younger brother, Yuuta Fuji. Fuji is particularly protective of Yuuta (probably to make up for former disagreements that almost brought them apart), as displayed throughout the series; he actively tries to "destroy" and punish those who have defeated his younger brother or have made him go through something dangerous (as proved by how differently he treats Jirou Akutagawa from Hyotei and Hajime Mizuki from Saint Rudolph. Though he holds no personal grudge towards Jirou, who won fairly against Yuuta, he does resent Mizuki for a long time after seeing how he treated his brother as someone expendable to ensure his team's victory).

Yuuta is also not the only person he has been protective of in this sense; in the anime, he is very upset when Kippei Tachibana is injured in his match against Rikkai Dai regular Akaya Kirihara (in the manga, Ryoma is the one who is injured). He is also upset when Akaya Kirihara insults the two schools, Seigaku and Fudomine. When Seigaku is down 1-2 in the Kantō finals against Rikkai Daigaku Fuzoku, he engages in a serious match with Akaya Kirihara, who plays a fairly violent form of tennis. Kirihara injures Fuji's knee and knocks over an already injured Tachibana, who arrives to encourage Fuji; thanks to this and the fact that Tezuka is also absent due to injury, Fuji becomes serious and goes on to win the match. According to what Fuji's sister, Yumiko, tells Hajime Mizuki and Yuuta, Fuji never gets angry about what happens to him, but when his family or friends are in danger, he does not hold back and attacks with full seriousness.

Fuji is fairly popular amongst his peers. In episode 134, he goes on a date with Kurumi, a grade schooler who falls in love with him at first sight, thinking of him as a prince of sorts. Despite his penchant for jokes and pranks off-tennis, Fuji can be insightful and even sweet when his friends need it; during his date with little Kurumi, when she reveals that she has low self-esteem since she feels overshadowed by her beautiful older sister Narumi, Fuji helps her to sort their problems out, seeing his own situation with Yuuta reflected in the sisters' quarrels.

Along with Tezuka, Fuji is possibly the only person on the entire Seigaku team who is immune to Inui Sadaharu's various concoctions. However, while Tezuka only appears unaffected and does not state what he thought of the concoctions, it has been a running gag in the story that Fuji actually "likes" those drinks and will recommend it to others too. While he may intentionally fault during practice occasionally in order to try the penal concoctions, he has also mentioned that he enjoys seeing others suffer from drinking the concoctions even more. He is, however, not immune to "Aozu", a horrific blue vinegar and cod liver oil concoction; this drink causes his only blackout, and since then, Inui has believed that Fuji has a grudge against him. His odd tastes in food do not stop at Inui's gruesome health drinks, and he takes delight in wasabi rolls, honey-mustard, and horseradishes.

At times, Fuji tends to act like Eiji Kikumaru, wanting to win and to be number one. In one episode, there is a mixed club day at his school, where the students are not allowed to play the sport that they are in. During this day, Fuji plays curling, which no one else plays, thus his words are, "No participants, the championship is mine."

Prior to the National Tournament, Fuji plays a practice match against Fudomine Chuu's Tachibana, who breaks each of Fuji's Triple Counter. Realizing that his counters are not enough for a national-level tournament, Fuji develops his Fourth Counter, Kagerō Zutsumi (Dragonfly Illusion). However, during Seigaku's National semifinal match against Shitenhouji's Kuranosuke Shiraishi, Fuji suffers his first loss in an official match, despite making a comeback from 0 games to 5 by using his evolved Triple Counter, he loses 6 games to 7 during a tiebreak. This is the first time that any of his teammates see Fuji so disappointed in the outcome of the match.