He's very witty and wise. He served Lieutenant Governor to Rou Ensei when he was the Governor for the Sa Province.

Spoiler

As the conflict rose, assassins were sent to kill both of them. As a result, Ensei set out on a journey to seek an audience with the Emperor in order to have a suited person assigned as Governor. During this time, Tei Yuushun chose to lock himself in a prison cell.