On their way back, Chu Guodong explained the identity of Li Sheng to Gu Yanzhi and Song Zhao.
It turned out that Li Sheng had also been a member of the Special Forces. More than a decade ago, when Chu Guodong had just enlisted, Li Sheng was his drill instructor.
Back then, Chu Guodong was young and brash, thinking he was fearless, and he had often been disciplined by Li Sheng. Despite this, they had a good relationship and chatted quite a bit in private.
Later, Chu Guodong joined the Special Forces after passing the selection process. Shortly after, Li Sheng got injured on a mission, damaging his internal organs, and could no longer stay in the military, so he chose to retire and switch careers.
