The only thing known about him is that he was a spy for a guild of space pirates and he married the daughter of Emperor Kotono in order to gain a position to learn Jurai's deepest sercets. Of their marriage, a daughter, Mitsuki was born. His wife died when Mitsuki was young.
When he discovered his daughter's powers, he asked her to spy on certain people and meetings to get information. Mitsuki was young and did not know what he was doing, but did it to make him happy. He sent information to his guild, who then attacked a minister from one of Jurai's ally nations. The attack destroyed most of the ships and nearly cost the minister his life. When it was discovered it was an inside job, he was implicated, but knowing that Mitsuki would not survive being banished from Jurai, The Supreme Council of Jurai allowed Azusa's uncle to become the scapegoat, leaving Syuuzen untouched, but also leaving his daughter confined in a special room.
When he discovered Azusa, who was his rival for the throne of Jurai, was secretly seeing Mitsuki, he revealed it to everyone and Azusa would have died if Seto had not intervened by blackmailing Syuuzen. Sometime later, Mitsuki would commit suicide to keep Azusa safe from her father's scheming
Candidate for the throne
When Kotono died, he was among the candidates to be elected for the throne, however, Azusa was chosen over him, which lead to the rivalry between Houses Amaki and Masaki.
It is unknown whether he is still alive. It was known he was alive when Yosho fled Jurai, but he is not mentioned after this.