In "Journey to the West", in addition to Sun Wukong, pig eight precepts, sand monks and other brothers who protect Tang monks, there is also a group of immortals who secretly protect Tang monks, he is four values of Gong Cao, five square revelations, six Ding Liujia, eighteen apologetics Garan and a total of thirty-nine protector gods.

Stills from "Journey to the West" (pictured)
So why did they protect Tang Monk? The reason is simple, because they are following the instructions of Guanyin Bodhisattva, doing both secret protection errands and recording and reporting. When Sun Wukong, pig eight precepts and other teachers and brothers exorcise demons and cannot take care of Tang monks, they play the duty of protecting Tang monks, and other times, they are more likely to act as "historical officials" or "reports", recording the hardships and tribulations experienced by Tang monks and apprentices along the way, recording the merits of Sun Wukong and other demons and exorcisms, and reporting them to the bodhisattvas in a timely manner.
So do the thirty-nine protector immortals, such as the Four Values Gong Cao, the Five Fang Revelations, the Six Dings and Six Jia, and the Eighteen Apologetics Garan, have names, surnames, and histories? Of course, there are, however, in this article, the author will not introduce them one by one, we will only make further explanations of the four values of Gong Cao, on weekdays, when watching mythological dramas, I often hear their names, such as a certain god said: "Where is the Duty Day Gong Cao?"
Mural of the Four Values of Gong Cao (Pictured)
The Four Values Gong Cao are the four gods and immortals worshiped by Taoism and folk beliefs, they are the four gods of the Heavenly Court, the Month, the Day, and the Time, so they are known as the "Four Values", which is equivalent to the duty gods in the Celestial Realm, and the Gongcao is their official name in the Celestial Realm. Gong Cao is the title and official name of ancient officials, also known as Gong Cao Shi, the western Han Dynasty, as the main adjutant and helper of local governments such as county guards and county orders, and the main work is to investigate and record merits, and to manage the merits. It was continued until the Ming Dynasty, when this official position was abolished. When Daoist theorists were weaving the celestial system such as gods and immortals, they also arranged this official position for the Jade Emperor and other great gods, of which the four-value Gong Cao was the most famous.
The four values of Gong Cao are four immortals, in charge of the duty year, the month, the day, and the time of duty, they are Li Bing, the god of the year, Huang Chengyi, the god of the moon, Zhou Deng, the god of the day, and Liu Hong, the god of the time. (Text: Repentance of the Past)