Itaru Saitō (齋藤至, Saitō Itaru) is the specialist who plans how the players can improve their play and train their mental mask. He devises who will compete against each other in a match.
He's in charge of the players' mental care, but also strengthening their mental state.By making the middle school partners play an elimination match, he actually trains the mental level of the players. In that sense, he is the strictest coach.
Saito has long black hair, which is frequently tied up in a low loose ponytail with long bangs framing his face. He has dark brown eyes, and is shown wearing a black turtleneck sweater with a white lab coat on top. He is also abnormally tall.
Since he appears he already tries the middle schoolers' mental strength as he says is even more important that the actual strength while playing: he tells the guys to pair up with whoever they want, leading them to believe that they'll have to play a double with that chosen mate. Instead, once pairings have been settled, he soon informs all of them that they'll have to match up against their partner, also including an extra factor: whoever loses the match will need to leave the camp and go home right away.
Having to face different players this way from the very beginning showed some players having trouble winning and send home their partner, or lose and go home themselves; a friendly fire that is still bitter to win.Whilst revealing those who have fallen behind in ability, he searches for the players who don't have the tenacity to win. That is the true purpose of the pair matches.
As promised, when all the matches have been concluded determining who's the winner and who's the loser, a bus will await for all the losers to bring them back home.
However, Coach Saitō will give a second chance to all the losers. To train their mental state, Saitō leads them into a bottomless valley. Trying their own will to pay back their winning partners and to remain in the camp: they'll have to climb an high mountain with nothing but their hands and showing to the coach their own mental strength. He is acquainted with Coach Nyudō, who specially trains the losers.
He is later seen silently watching Echizen Ryoma, Oshitai Kenya, and Tanishi Kei during the "Special Mission" through the security room, commenting on how this year's three were skilled, implying that Coach Nyuudou's special mission is planned and happens yearly.
- Hobbies: Mind sports, observing ants, daydreaming as he stares at the ceiling while lying for ten minutes. (Saitō's Comment: Sports where you use your head. Observation. And looking at the ceiling when I'm bored. And then, hitting my forehead...... I'm joking.)
- Favorite color: White and Gray
- Favorite food: Mille-feuille (A type of pastry)
- Most wanted thing at the moment: Nest of transparent ants
- Thing/s that he is bad at/dislikes: His wife
- Specialty other than tennis: Counseling
- According to Otori, Coach Saitō' talks a lot about Hyotei Tennis Club's coach, Taro Sakaki.
- He dotes on his daughter.
- He is a bit careless/absent-minded.