Sima Yu
Sima Daozi was born in 364, two years after his older brother Sima Yao was born to their father, Sima Yu, Prince of Kuaiji, and mother Consort Li. In 371, after the paramount general Huan Wen deposed Emperor Fei to showcase his power, he made Sima Yu emperor (as Emperor Jianwen). In 372, when Emperor Jianwen grew ill, he created Sima Yao crown prince and Sima Daozi the Prince of Langye. He died soon thereafter, and Sima Yao assumed the throne as Emperor Xiaowu.