In the Trebian Empire mines, Aren and Toa led a life of harsh labor for 10 years. It was Aren dream to escape the mines together with his younger twin sister, Toa. However, it did not come into fruition. Toa ended her life through suicide. Losing the motivation to live without his sister, Aren commits to ending his own life. However, a mysterious figure nicknamed Deed appears before him. Deed claims there is a method to revive Toa if Aren makes a contract with Deed…?