 He served at Gong'an County in Jing Province as a subordinate of the general Guan Yu, who was appointed by the warlord Liu Bei to guard Jing Province.Following a dispute with Guan Yu, Shi Ren and Mi Fang defected to the warlord Sun Quan when Guan Yu was away at the Battle of Fancheng.Shi Ren and Mi Fang allowed Sun Quan's forces to overrun Jing Province, leading to Guan Yu's defeat and death.