For thousands of years, no one can tell clearly when the shadow appeared. However, as the historical trend continues to flow forward, the shadow has become an inhumane tyranny. Once a crime is committed, no matter how old or young, they will be thrown into the training ground - the "Shadow Valley" like Shura Field. People who enter the "Shadow Valley" have only two ways, one is to become a "shadow" who absolutely obeys the master's orders, and the other is to die. The shadow cannot violate the will of the master, nor can it do anything to harm the master. In other words, everything will be based on the master.
Shadow is a person who has committed a serious crime and survived many difficult martial arts and magic training, so he has a certain degree of strength. After completing the training, each shadow will be assigned to a warrior who has the magic power to control them. It exists as a weapon to strengthen the warrior's strength, so the shadow has no life value.