The following characters reside in the Kingdom of Kei:
Youko Nakajima is a sixteen-year-old
honors student in Japan who lives an ordinary life. Her primary worries are her naturally red hair (it was speculated by some students and a teacher that Youko might've dyed her hair red) and an inexplicable recurring dream that haunts her. When a man named Keiki suddenly appears at her school, he bows at her feet, swearing loyalty to her and offering protection. The school is attacked by a giant bird and she reluctantly accepts his oath. He gives her a sword and transports her across the Void Sea to the Twelve Kingdoms, where she ends up in the Kingdom of Kou. Youko is initially confused by the changes that have been brought onto her including a complete change in her appearance that she cannot see herself and being stranded in an unknown land with no means of returning home. These changes cause her to cry constantly, lapse into a state of helplessness, and complain about interfering in other beings' lives no matter what the situation. As she searches for Keiki, she finds herself constantly battling against Youma and being betrayed by civilians of Kou many times. While Youko becomes wary of trusting others, she eventually comes to befriend and trust a hanjyu named Rakushun. They escape to the Kingdom of En where Youko learns that she is the heiress to the throne of the kingdom of Kei. Although she is initially reluctant, Youko accepts the position through her growth in the story. In a later story arc as the newly appointed queen, Youko learns of several problems in her kingdom including a revolt in the Province of Wa. Subsequently, she is pulled into the search for Taiki when the Tai general Risai beseeches Youko's help in finding him. As the ruler of Kei, she is given the
regnal name of , because of her bright red hair and because her
councillors initially view her as a child. Despite being a weak character to begin with, appearing very withdrawn and not wanting to do anything that would bring attention to herself, Youko grows in strength and maturity, becomes empathetic towards the people around her, thinking articulately about her actions (especially as queen) and continues to do so until the end of the series.
Aozaru is the physical manifestation of the sentient spirit of the scabbard of the . The sword is a royal treasure to the kingdom of Kei and can only be wielded by the kingdom's rightful ruler – as such, Youko is the only one who can draw the sword from its sheath. The sword was forged from a water demon that a previous great ruler of Kei had defeated while the scabbard was created from a long-tailed
monkey demon. From the scabbard hangs a large jewel that can heal the one who holds it. The sword is not only capable of killing demons and
sages and breaking substances like metal chains, but is also capable of presenting visions of the past, future, and things in the distance. The sword and scabbard must be kept together, otherwise the phantasms of the sword appear unchecked while the spirit of the scabbard is free to act as it wishes. When Youko loses the scabbard during an attack by Kikis, it appears in the form of Aozaru, the blue monkey, and taunts her with her doubts while the sword presents her with visions of things she does not wish to see. Eventually, Youko, overcoming her own doubts, kills the monkey and picks up the dead scabbard. Because she has killed Aozaru, the sword can be drawn from the sheath by anyone, though it can be wielded effectively only by Youko.
Seikyou has long served as the Chosai, the top administrator, of Kei. Seikyou works to convince Youko that Koukan, the leader of the province of Baku, is a threat to her. After an assassin plots to kill Youko, Seikyou advises Youko that Koukan planned it and that she should execute him, but Keiki advises her to listen to Koukan before acting. When Youko orders Koukan to report, Seikyou has him attacked, forcing him to flee. Seikyou continually seeks to confuse Youko, telling her that Gahou is corrupt but advising that no action be taken against him, even though Seikyou secretly supports Gahou. He repeatedly seeks meetings with her when Keiki is not present so that the kirin cannot advise her. Youko, citing Seikyou's attempts to manipulate her and his failure to better safeguard her life, demotes Seikyou and appoints Keiki as chosai. When Youko leaves to study with Enho, Seikyou takes advantage of the situation to usurp Keiki's authority. When the rebels become a threat to Gahou, Seikyou sends a royal army force under general Jinrai to Shisui to scare the rebels into surrendering, unaware of Youko's presence in Wa because she told everyone in the court except Keiki that she was going to En. Seikyou's plan fails because Youko appears to take control of the royal forces and she redirects them against Gahou. After Shoukei convinces Youko that Seikyou is the mastermind behind the plot, Youko has him arrested.
Ei Province inhabitants The following characters reside in the Kingdom of Kei's capital called the Ei Province:
Keiki is a
Kirin and the Saiho of Kei. Like all Kirin, Keiki abhors violence and prefers peaceful resolutions. Keiki appears as a very quiet and unemotional type, however does have caring qualities, especially seen towards the Kirin Taiki. In spite of being gruff and somewhat unapproachable, he is actually very sincere and loyal to Youko. Before meeting Youko, Keiki had taken a long time before selecting Youko's immediate predecessor, , to become the ruler of Kei, but she was an ineffective ruler and fell in love with Keiki; her jealousy resulted in irrational acts including expelling all the women from the country and executing those who remained. Keiki contracted Shitsudou and in order to save his life, Joukaku abdicated her throne and killed herself after a short reign of six years and was posthumously known as . Cured of his illness, Keiki set out immediately to find a new monarch for Kei. He eventually finds Youko Nakajima, who had been living as a taika in Japan without any knowledge of the Twelve Kingdoms, and forcibly brings her back to the Twelve Kingdoms. They are separated on arrival and Keiki is captured and enchanted by Kourin, the kirin of Kou, so that he is unable to speak, summon his Shirei, or return to human form. Forced to appear before , Joukaku's sister and pretender to the throne of Kei, Keiki remains a prisoner of the false ruler until Youko, aided by the King of En, rescues him and frees him from his enchantment. After liberating Kei, Keiki continues to advise Youko on statecraft and politics.
Enho is a wise man who lives in the city of Hokui in the province of Ei, where Keiki is the provincial leader. When Youko decides that she knows too little about her kingdom to rule wisely, Keiki sends her to Enho to study. Among the citizens of Kei, only Youko, Keiki, and Enho know of this arrangement. When she arrives, Enho's Rike is under attack by youma, and she acts to save Enho and the rike's other residents, but only Enho, a girl named Rangyoku, and her brother Keikei survive. When Youko leaves to visit Takuhou and Meikaku, the rike is attacked by Shoukou's men; Rangyoku is killed, Keikei is injured, and Enho is abducted and taken to Gahou. Youko moves to rescue Enho and learns from Suzu that Shoukou has taken Enho. When she captures Shoukou, he reveals that Enho is held by Gahou. Enho is rescued when Youko sends the royal army to attack Gahou and she appoints him as her
Taishi, one of her chief advisors responsible for educating her on matters of state. Enho is known by a number of aliases; his true name is actually . Under the name , Enho was known as a legendary higher sage who served , a great and beloved Emperor of Kei, and was responsible for sealing Aozaru into the Suigūtō's sheath. During this time, he was also known as .
Wa Province inhabitants The following characters reside in the Kingdom of Kou's Wa Province:
Shoukou is the governor of the Shisui Prefecture in the Wa Province of Kei. His corruption is so great and the taxes he demands are so high that he threatens the fragile stability of Youko's rule as the new Queen of Kei. When Shoukou's carriage runs over the blind boy Seishuu, Suzu convinces a resistance movement led by Koshou and Sekki that the time has come to rebel against Shoukou. Youko joins with the rebels when she discovers that Shoukou is responsible for abducting her mentor Enho. In the anime, Shoukou enlists the aid of the half-crazed Asano and appears slim, confident, and defiant of the Heavens' will, but during his sword fight with Youko, when he realizes that he is fighting the ruler of Kei, he gives up. In the novel, when Youko finds Shoukou, she discovers that he is immensely fat and he is futilely trying to hide from her. In both media, Suzu insists that Shoukou be killed, but Youko refuses to allow anyone to kill Shoukou since she needs to question him about who has been allowing him to get away with his crimes.
Gahou is the corrupt leader of the Wa province of Kei. Gahou orders Shoukou to kidnap Youko's mentor Enho because he believes that Enho's idealism is a threat to him. Shoukei swears to depose him after she witnesses a crucifixion Gahou ordered, leading to her joining a resistance movement led by Kantai. When Shoukou is captured, because Gahou fears that his lackey will reveal damaging information that will lead to his dismissal, Gahou sends a military force to wipe out both the Shisui rebels and Shoukou, a plan foiled by Kantai's timely parallel effort to relieve the rebels with his own force. When Youko takes control of a royal army force sent by Seikyou and led by general Jinrai, she sends the force to arrest Gahou and free Enho.
Koshou is the charismatic leader of the Shisui rebels. He rallies the rebels to fight against Shoukou, even though he believes that they cannot win. When Youko declares that Shoukou must be spared, Koshou supports her. When the town of Takuhou, the capital of Shisui, is set on fire, Koshou insists that the people must be rescued or else the rebellion has no point, even though the fire is a trap for his fighters. When Youko asks him what he wants as a reward for his service, he asks her to procure a university spot for his brother Sekki.
Sekki , the brother of Koshou, is the brains behind the Shisui rebels. When Youko appears searching for Enho, Koshou is about to attack her because he believes she is a spy who is going to give them away, but Sekki stops him. He later explains that he heard the ring of steel, and that Youko's bravery suggests that she is far more dangerous than she appears. Sekki makes all the tactical decisions for the rebels except when fire threatened Takuhou and Koshou overrides him.
Baku Province inhabitants The following characters reside in the Kingdom of Kou's Baku Province:
Kantai is actually , the
general of the province of Baku. He is a Hanjyuu that can take the form of a large bear and he is incredibly strong even in human form. He saves Shoukei after she ran from the soldiers who sought to arrest her after she threw a rock at Gahou's executioners. Kantai seeks to expose the corruption of Gahou, and he sends Shoukei to the intermediate village of Houkaku to provide touki weapons to the Shisui rebels. Suzu arrives there to take the weapons to Takuhou. When Kantai realizes that his allies in Shisui will be wiped out by Gahou, he sends his own forces to intervene. Shoukei accompanies him and seeks out Suzu to inform the Shisui rebels that Kantai is on their side. When Koushou insists on saving Takuhou from fire, Kantai is shamed into helping him despite his doubts. When Youko asks Kantai what reward he wants for fighting corruption, Kantai asks for pardon for his lord Koukan. After Gahou is defeated, Youko places Kantai in charge of Kei's entire army.
Koukan is the leader of the province of Baku. Of all the provincial
lords, only Koukan opposed the false queen Joyei. Seikyou advises Youko that Koukan will oppose her as well and when a trusted advisor attempts to kill Youko, Seikyou argues that Koukan is behind the plot. Youko suspects Koukan, but she does not act on her suspicions due to the advice of Keiki, who argues that Koukan is not the sort of man who would come up with such a scheme. When she orders Koukan to appear and explain himself, he is attacked and forced to flee and go into hiding. Youko eventually learns that not only has Koukan been falsely accused, but he has taken the initiative to try to stamp out corruption in the Wa Province by sending his top general Kantai to the Wa capital of Meikaku. She rewards him for his efforts by promoting him to chosai, the chief administrator of her court. ==Kingdom of En inhabitants==