Liu Zerui is a police officer from the "90" post-90s police detachment of the Kaiyuan Public Security Division of the Kunming Railway Public Security Bureau. Since the launch of the China-Laos Railway international passenger train on April 13, 2023, he, who is a highly qualified police officer, has been on duty for this train.

Liu Zerui's every move is under the lens of the real-time visible law enforcement recorder. Every safety inspection on the train needs to be dictated by him.