In 344, another nephew of Sima Yu, Emperor Kang (Emperor Cheng's younger brother), died, and was succeeded by his infant son Emperor Mu. Emperor Mu's mother Empress Dowager Chu became regent, but she largely followed the advice of prime minister He Chong (). As it was customary, at this point of Jin history, for there to be two prime ministers, He Chong recommended Empress Dowager Chu's father Chu Pou (), who declined and recommended Sima Yu instead. He Chong and Sima Yu thus shared the prime minister responsibilities until He Chong's death in 346. He Chong was replaced by Cai Mo.