One day, six cards known as the "Six Desires" were born with the power to change fate. 
Six fighters were chosen, and would come to possess those six cards. What awaited them was the “Fated Clash“, where they would fight each other until the end, and the last one standing would have any wish granted. A youth named Akina Myodo, who wants to help his frail sister, participates in the Fated Clash to have his wish granted.
 
And thus, he throws himself into battles with powerful fighters. 
(Source: Crunchyroll)