In a world where everyone’s lives are controlled by luck, people exist in three identical versions. The three share an energy called Tera. The one with the largest share of Tera is called the Root and the others are called Subs. If the Subs meet, they perish and leave all the Tera to be absorbed by the Root. The Root would then possess an enormous amount of luck. Higher beings who maintain the balance of Tera are called the Tera Guardians. A Tera Guardian named Kuro meets a boy named Keita.