The 7 major titles mentioned are Kisei, Meijin, Honinbō, Jūdan, Tengen, Ōza, and Gosei.
Sai's ghost had previously possessed the real-life figure Honinbo Shusaku who became a renowned Go player.
After the legendary match that ends with Sai's triumph by the narrowest margin (a ½ point), Hikaru discovers another move which would have turned the game around.
Extremely effeminate by today's standards, Sai is often drawn with traditionally feminine features and mannerisms.
Yumi Hotta has joked about fans mistakenly calling him a "she" in the "intermission" pages of the manga.
Sai's extremely emotional behavior is also proper for a Heian male; he sometimes cries copiously in chibi style, soaking his long sleeves with tears, which in his own time would be respected as a sign of intelligence and sensitivity.
As the series goes along, the plot brings these two characters together to play each other under different circumstances, each time adding to the mystery.
She learns a little bit about Go, when Hikaru becomes interested, and she later joins the Haze Middle School Go club, serving as vice captain of the girls' team, despite her being a weak player.
Initially he relies on a strategy book, though he has excellent Yose (end game) skills.
Kaga hates Go and prefers Shogi because his father forbade it and forced him to play Go from an extremely early age, and he could never please the old man no matter how well he did, because he always lost to Akira Toya.
He is angry at Hikaru for choosing to be an Insei rather than stay at the school Go club when they have a tournament around the corner.
Kumiko Tsuda is one of Akari Fujisaki's friends and student in Haze Middle School.
He is also known to be very reckless and short-tempered, even punching former Insei Mashiba in the face because the latter rattled his friend Isumi.
The match weighs on his mind and he loses his next two games and the chance to become a pro, ultimately ending with four losses.
There, he learns to control his emotions and passes the next year's pro exam without a single loss.
Yet another Insei in the same group as Hikaru, Ochi is one of the youngest (12 years old when introduced), yet very outspoken about his ability.
His bragging about his strength hides his insecurity; after each loss he is known to disappear into the restroom for long periods of time.
Ochi loses to Hikaru, but does pass the pro exam with the highest score and only two losses.
He almost makes the top three players in the professional exam, even managing to beat Hikaru, but ultimately fails.
Kadowaki is a cocky player who initially applied to be an insei before Sai plays for Hikaru and easily beats him.
Nicknamed "Fuku" (フク), an Insei and classmate of Waya who is known for his extremely fast-paced style of play.
He fails the pro exams, and due to the age limit of 30 will never be able to retake it again, so he asks Hikaru to win in his place.
He played Akira Toya in the Shinshodan Series, and was angered by his precocious attitude, resolving to crush him.
Akira dominates most of the match, but his excessive risk taking allows the Oza to turn the game in his favor.
He worked as a go instructor for children in Korea, and was initially disappointed in young Go players in Japan, until he joined the Kaio faculty.
He claims his brother bought the board in an antique shop, intrigued by the rumor that a "ghost in a tall hat" would appear from it sometimes.
A girl who works at an internet cafe and lets Hikaru play Go on the computers for free during her shifts.
Having turned pro at the age of 11, Le relocated from his hometown in Yunnan to Beijing to study at the Chinese Go Institute, but his skills had been stagnating as he was distracted by the life in a big city.
Heated words between him and Hikaru lead to the two playing an intense, exciting match at the Go salon.
He unintentionally caused a lot of tension between Team Japan and Team Korea surrounding the tournament, as a bad translation of his Korean words during an interview caused people in Japan to think he insulted Honinbo Shusaku.