|Traveler of the Void|
|Title||Traveler of the void|
|Romaji Title||Kokū no Tabibito|
|Illustrator|| Makiko Futaki|
| Preceded by|
Guardian of the Dream
| Followed by|
Guardian of the God
|Publisher|| Kaisei-sha (hardcover)|
Traveler of the Void (虚空の旅人, Kokū no Tabibito) is the fourth novel in the Moribito series written by Nahoko Uehashi. It is the first book to feature Chagum as the protagonist and considered part of the "Tabibito" strand of the series.
Though the events of Traveler of the Void occur after Guardian of the Darkness, knowledge of the events of the second novel are not required to understand the events of Traveler of the Void. When Chagum and King Radalle meet in Sangal, neither are aware of their shared acquaintance of Balsa.
Chagum, now the crown prince of the New Yogo Empire, and Shuga are sent bearing greetings to a southern country, Sangal, for the new king's coronation ceremony. However, a black shadow is reaching towards Sangal and the would-be-king of Sangal is fatally wounded.
Fourteen-year-old Chagum is accompanied by Shuga as they arrive in the royal palace in the kingdom of Sangal. As the Crown Prince of New Yogo, Chagum has been sent in the place of his father, the Mikado, as an honoured guest at the ascension ceremony of Karnan, the heir of the king of Sangal. Chagum quickly befriends Saluna and Tarsan, members of the Sangal royal family.
Meanwhile, a secret envoy of the Talsh Empire, disguised as a merchant, begins a plan to manipulate the Island Guardians, governors of the individual islands of Sangal's archipelago, to revolt against the kingdom, with Island Guardian Adol as the leader. Though the royal women of the Women's council have already noticed some suspicious activity, but they cannot yet decipher merchant's secret messages and have no direct evidence to press charges against him.
On Kalsh Island, a six-year-old girl named Eshana (エーシャナ) has become Nayugul Lighter's Eyes - believed to be possessed by the spirits of Nayugal Lighters, the residents of a mythical sea beneath the sea called Nayugal. Eshana is the only daughter of a local genius diver, Yata, who had once been the teacher of Tarsan and a Rassharou girl named Surinā (スリナァ) and has since disappeared. As the Nayugul Lighter's Eyes, Eshana is brought to the royal palace and made to attend receptions and parties celebrating the throne ascension. The Talsh envoy, revealed to be a magic weaver, makes a brief contact with Nayugul Lighter's Eyes before her departure to Sangal capital. The day after Eshana arrives in the capital, in front of honorable guests, Tarsan throws a treasured harpoon towards Karnan and seriously wounds him.
Shuga soon discovers that Tarsan is under Yogo-originated evil magic charm, however, he has no physical evidence, while Tarsan has no memory of the event. To save Tarsan from execution in the coming days, Saluna secretly breaks him out of prison and they hide in Chagum's private chambers. Karina, the leader of the Women's Counsel and the wife of Adol, becomes aware of their location but does not move to capture them.
Chagum's group soon realizes the Talsh Empire is conspiring to disable Sangal's military command chain to simplify their invasion. Furthermore, they discover that a magic weaver is using the body of the Nayugul Lighter's Eyes to coordinate the conspiracy. Due to Shuga's inexperience, he is unable to drive that magic weaver of Eshana's body. By the time they share their discovery with Karina, the royal family has already become aware of upcoming Talsh attack, having obtained valuable intelligence on the Talsh fleet from Surinā, who obtained the information from a Rassharou man. Chagum sends messengers to warn New Yogo of the impeding threat.
The Talsh magic weaver orders Adol to assassinate Tafmur, the current king of Sangal, and Karnan. Adol decides to simultaneously kill both Tafmur and Karnan during Nayugul Lighter's Eyes soul return ceremony. He makes a written pact with other Island Guardians making them to personally participate in king's murder during the ceremony. Still recovering from his injuries, Karnan does not attend the soul return ceremony and instead attends a royal banquet with honourable guests to celebrate his health. With no royal guards or weapons permitted in the banquet hall, Adol arranges for assassins disguised as a dancing troupe to infiltrate the banquet.
Though Karina has seen through the upcoming assassinations, she has neither proof nor details to act and asks for Chagum to act during the banquet. Chagum successfully arranges for the personal guards of the kings of Sangal and Rota to be placed around Karnan during the banquet to protect him, foiling the assassination and resulting in the deaths of the assassin squad.
At the site of soul return ceremony, Tarsan suddenly appears and stops Island Guardians' attack on Tafmur. However, the Talsh magic weaver finally reveals himself and uses Eshana's body to strike a poisoned needle into the king's neck and forces everyone to obey his orders. At Karnan's banquet, the shock of the massacre he has arranged causes Chagum's soul to temporarily leave his body in a desperate attempt to save Eshana. His soul proves powerful enough to force the Talsh magic weaver from Eshana's body and the Talsh magic weaver flees when Shuga's soul arrives to assist, unable to confront two opponents at once.
As Eshana's body is freed from the Talsh magic weaver's control, a fearful Tafmur orders her body to be thrown into the sea. Surinā and Tarsan rescue Eshana as her soul finally returns to its body. Though Surinā and Eshana are imprisoned soon after, Shuga arranges for their release.
The novel ends with Tarsan departing to go to war with the Talsh Empire and Chagum returning home.