Tegiru Rowun is a character who appears in the sequel Fushigi Yuugi Genbu Kaiden, where he is a major antagonist for a period of time. He is the emperor of Hokkan after his brother Temudan Rowun, and before his nephew Limudo Rowun.
He is described as ruthless and complete opposite of his older brother, Temudan. He even dislikes his own daughter, mainly because she was born a girl. He also seems to be quick to lay around with his female attendants, despite Kutou declaring war on the country.
When he and his brother went hunting years ago, before Hokkan fell under Tegiru's supremacy, he even imprisoned one of the Genbu Warriors, Hagas's twin brother, Teg; he has a strong fear and hate towards the Priestess and her warriors and will do what he can to eliminate even those who serve filial piety towards her.
It was briefly stated in the manga that after his brother, Temudan caught the deadly disease from their hunting trip, he realized his ambitions for the throne were great, and so he elaborated a scheme. He and the false oracle worked together to do away with Rimudo when he was born, because he would have been the rightful ruler to rule all of Hokkan. Tegiru didn't want that standing in his way, so he negotiated with the false oracle and had her tell a false prophecy that when the priestess summoned Genbu, Rimudo would kill his father, Temudan. Because of this, Temudan was sent out of the palace and into another and Tegiru took his place on the stolen throne.
Tegiru is the younger brother of Temudan Rowun, and second-in-line for the Hokkan throne. In Chapter 35's significant flashbacks, it was revealed that he and his brother went hunting together, and on the process they came across the monster that inflicted his brother with the "incurable disease", changing the fate of Hokkan forever.
When their father, the emperor, learned of his eldest son's sickness, a powerful fortune teller hired by Tegiru delivered a false fortune to the Rowun family and said that Temudan was never going to recover (but in truth, he did, and he could: the true prophecy said that Temudan would die, but only when the Genbu Senshi were reunited). Hence, the throne was given to Tegiru, and he ruled ruthlessly for many years while Temudan was exiled to a castle at the back of the palace. Tegiru also keeps one half of the Urumiya twins, Teg, imprisoned while the other, Hagas, is taken away and ultimately serves Temudan.
Tegiru also rejects his daughter, Efinluka Rowun alias Firuka, solely due to being a girl. She ultimately runs away from the court and becomes a priestess.
When Temudan was officially enthroned after a rebellion, he had Tegiru imprisoned and bound. Later he had him brought forcibly to his presence and sentenced him to death - a sentence that Hagas carried out by cutting him up alive: his left leg was amputated, his left arm followed, then his left eye was torn out, and he ultimately was decapitated. Even in his middle of this gruesome execution (which is not fully shown, but depicted through discretion shots), Tegiru refused to recognize Temudan as the Emperor, taunting his brother about the upcoming destruction of Hokkan until Hagas beheaded him.