Tei Yuushun

Tei Yuushun (鄭 悠舜 Tei Yūshun) is the former Advisor of the Governors of Sa Province and Prime Minister of Saiunkoku.

Personality & Characteristics
Yuushun is a mild-mannered man in his late thirties who walks with a cane. Despite his gentle exterior, Yuushun is considered to be dangerous and very powerful. Yuushun is an effective politician who can accurately predict the current situation, and can be so persuasive in debate that the Merchant's Guild was reluctant to even enter negotiations with him.

Plot
Ryou Anju says that Yuushun is from a noble family that even surpasses the power of both the Ran and Kou Clans. His family is actually the clan of Hourins, the Ki clan, a retainer of the Kou Clan  which secretly lived. Every few generations a member was chosen as the Hourin who will protect the Kou clan from its greatest danger. Before Yushuun is the current 'Hourin' and the previous one was his great grandmother.

Initially appearing as one of Shūrei and Eigetsu's assistant officials in Sa Province, Ryūki promotes Yūshun to Prime Minister, giving him a feathered fan as a sign of office. Yūshun's political actions disturb the noble families enough to potentially endanger his life; despite his protests that he does not need protection, Seiran is assigned as his personal guard.

During Ensei's term as governor of Sa province, Yuushun serves as his assistant. When Ensei resigns the position and leaves, Yuushun remains there as the temporary governor, performing his duties while voluntarily locked into a tower to protect him from the Sa clan. Yuushun loses his official status and is left in a dangerous position when Shuurei and Eigetsu are appointed as co-governors of Sa province, but Ensei assures them that Yuushun will be entirely safe, even from Sakujun Sa.

Yuushun first appears in the 28th episode of the anime's first season as an official sent from Koren to help Shuurei and Eigetsu, who had just arrived in Kinka. Under the alias of Official Yū Jun, he readily gives advice to the young co-governors. Only Ensei knows his identity, and the two men work closely together to support Shuurei and Eigetsu. Yuushun orders the military forces throughout the province to quell the riots instigated by Chuusho Sa, and to capture the corrupt members of the Sa clan. When Shuurei and Eigetsu find out that "his" tower has burned down, he reveals his real identity as Yuushun Tei and says that he was rescued by Ensei's master, who extracted him from the locked tower and left him on the streets of Kinka, where he revived the next day.

Ryuuki promotes Yuushun to Prime Minister, giving him a feathered fan as a sign of office. Yuushun's political actions disturb the noble families enough to potentially endanger his life; despite his protests that he does not need protection, Seiran is assigned as his personal guard.

Due to some mysterious reason, all records of his past were erased. Only a handful of people are aware of his past and those who knows his true self are really scared of him. At times he is considered even dangerous than Anju himself. His title 'Hourin' is title that holds a special meaning. It is hinted that he was the one who sent assassins after Seiga and Shuurei during their mission. It was the 'Hourin' who turned the people of Kou clan against their leader with his influence, and the 'Hourin' is none other than Yuushun as mentioned by Seiga. When Yushuun's family was destroyed because Reishin's father sold them out and Resihin didn't help him, the emperor Senka found him unusual and asked if he would like to serve him. Yushuunwho was without any human emotions at that time simply replied he did not. He told Senka that he found his existence even more insignificant then a peach. When Senka allowed him to eatthe peach before his deathhe said smiling that he will bury it and it will becomea peach forest and an ideal grave for the Ki clan. Senka was shocked and thought of him a sthe greatest villain there ever will be. He let the boy live because killing him will mean he is afraid of that child. Thus, Ou Ki found him and saved him.

Yuushun was planning on helping Ou Ki become the emperor but in the end as he saw Ryuuki's trust in him and kindness for him despite the fact that Ryuuki was made aware of his true allegiance by Seiran, he chose Ryuuki as his master and decided to change sides and fought for Ryuuki in the final battle which turned the tables causing Ouki's downfall.

After everything ended, it was revealed that he was still Ryuuki's prime minister and he was revealed to be a father-to-be along with Reishin. He didn't live much long after Ou Ki's fall. He fathered two children with his wife.

Sai Rin
In the novels, he was in love with Sai Rin, Sai Shou's twin sister, even before Rin proposed to him, but he never thought that he had a chance because of the age gap. He kept rejecting her proposal year after year because he didn't want her to get involved in the Sa conflict. This made him very depressed, and also caused much drama for Ensei and Sai Sho. When Sa province is finally under control, he accepts Rin's proposal in the Autumn Festival and they are married. They are referred to as newlyweds in episode 38 of the first season anime. They have two children together.

Kou Reishin & Kou Houju
Yuushun is a very good friend of Kijin and Reishin, who both took the official exams with him. In the trio, he is older by a few years. He passed first in the Exams (with the title Jogen), with Reishin passing second (Bogen) and Kijin third (Tanka).

Kou Shuurei
A side story of the manga shows that he first met Shuurei during her childhood, when she gave him some of her homemade buns. And in the anime it shows that Yuushun secretly watched Shuurei during her childhood.