Sister-sister relationship.
Tong Chengchou, the late head of Longmen Escort Bureau, was Tong Xiangyu’s younger brother. In episode 12, Tong Chengchou and Tong Xiangyu recognized each other.
Longmen Escort Bureau was originally a famous escort bureau in Shuhe Town, but after the death of its original boss Tong Escort, it was heavily in debt. In order to make money, Cai Badou went to the Longmen Escort Bureau to collect debts, but he fell into a trap and was imprisoned together with Lu Sanjin, the young master of Ping An Bank.