The Jiantian Si Tidain (Chief Astronomer) of the Directorate of Celestial Observation. He last saw Xie Chengze on the night Consort Hua passed away, when the Second Prince had a breakdown and smashed instruments. He is initially fearful of Xie Chengze's sudden visit but becomes amazed by his mathematical skills. He agrees to help Xie Chengze with a favor in exchange for solving geometry problems.
