Cai Shen or Bi Gan, his mortal name is literally translated as the God of Prosperity. Cai Shen is one of the most popular pantheons among the Chinese community. His popularity is due to his primary duty as an accountant guarding all the treasuries on heaven. He is also able to bestow fortune to suitable candidates on earth. Though Cai Shen is mainly perceived as a Taoist deity, Pure Land Buddhism also recognized him as a god.

Historically, Bi Gan was the uncle and a minister of King Zhou of the Shang Dynasty. He was also a very honest and capable business man. Often Bi Gan would offer his helps to other merchants by funding their business with no obligations. The poorer folks also benefited from Bi Gan’s generosity as he would donate his wealth and fortune to them. Thus he grew tremendous amount of popularity among the people. The popularity that Bi Gan received from the people soon draws the jealousy of King Zhou and his family. Daji, King Zhou’s most favored concubine one day killed Bi Gan by digging out his heart. After his death, business man started to hang the portrait of Bi Gan to honor him. Those who had hung the portrait of Bi Gan also swore to the heaven that they held upmost honesty in doing business. The death of Bi Gan soon marks the end of Shang Dynasty.

According to legend, Bi Gan did not die. He was offered a magical panacea by a hermit Zhang Ziya that prolonged his life. Bi Gan escaped to the woods with his wife, children and fortune. Often he would appear from the woods and continue to distribute his wealth to the people. The magical panacea had prolonged his life unnaturally until he had finally attained enlightenment on top of a mountain. Legend also state that he co assists with Taoist master Zhang Dao Ling in search of secrets of life prolonging panacea.

Cai Shen is depicted riding a black tiger holding a metallic rod as his weapon. The usual portrait of Cai Shen is a man dressed like a civil official who wears a minister's gauze cap and embroidered robe, with a Ru Yi (an S-shaped ornamental object, usu. made of jade, formerly a symbol of good luck) in his hand and gold or silver ingots under his feet. His portrait is usually hung during Chinese New Year. Business man, investors, traders and gambler would often pray and seek advise from the Cai Shen and mistaken him as the God of Luck.