The story of Saiyuki is based on the Chinese classic fantasy novel The Journey to the West, also one of the Four Chinese literature masterpieces.
The story begins when the prisoned demons and evil spirits in Heaven, who broke the prison on the by defeating celestial guards when the Peach Banquet in Heaven was on.
These demons and evil spirits, who had stolen many treasures from the Heaven, then created many mirror images and hid themselves with treasures all around the world, just to avoid the hunt of Heavenly Generals and Soldiers.
At meanwhile, Emperor Taizong of Tang Dynasty sent Monk Tang (“Sanzang” in short) to the West for the supreme Buddhist scripture from Buddha.
With the help of the Goddess Guanyin, Sanzang successfully gained three competent assistants, namely the famous Monkey King, the Great Sage Equalling Heaven, Monk Pig, the Marshal Tianpeng and Friar Sand, the Curtain-Lifting General.