Yin and Yang are two minor elemental G.o.ds in the Celestial realm. Because of their polar personalities they are constantly at each other 's throat. One day, their brawl resulted in the Celestial Emperor 's favorite wine cup being smashed to the ground. Enraged, the Emperor sentenced them to a mortal trial in a desolated desert, so that they can learn to live in harmony and cooperate with each other...