|Occupation||Star Reader, Sagum's tutor|
|Location||New Yogo Empire|
|Novel||Moribito: Guardian of the Spirit|
Gakai is a Star Reader and the tutor assigned to First Prince Sagum. Depicted as a proud man, he appears to look down on Shuga, who is his junior as a Star Reader and as the tutor to the Second Prince, Chagum. He is a stern man who expects Sagum to take his studies seriously and not to be distracted by personal or sentimental reasons, particularly because Sagum is expected to succeed the Mikado.
While Gakai maintains an arrogant attitude and unfriendly relationship with Shuga in the novels, Gakai develops into a more sympathetic character in the anime series. When Sagum unexpectedly dies from overworking himself and falling ill, Gakai withdraws from his duties and thinks that he is useless now that Sagum is dead. When Shuga approaches him for help in deciphering the ancient tablets in the imperial archives, Gakai initially believes Shuga, now the tutor to crown prince, has come to gloat. However, Shuga expresses his sincere respect for Gakai as a scholar and how Gakai's abilities are needed to save New Yogo and Prince Chagum.
Gakai agrees to the request and manages to decipher the majority of the tablets, allowing Shuga and the Hunters to prepare an adequate defence for Chagum. However, Gakai is horrified to discover upon deciphering the last tablet that their preparations have been based on a grievous error regarding the location at which the Water Spirit will be born. Gakai immediately sends a messenger to deliver the message to Shuga in order to save Chagum.
When Chagum returns to the imperial palace, he quietly expresses gratitude towards Chagum for returning when the young prince visits Sagum's room.