In the near future, humanity awoke to a new power known as "Septima." Humans with this power became known as "Adepts," and steadily increased in number as new Adepts were born. An organization of these Adepts, "Eden," attempted to secure their supremacy over the world, only to have their ambitions ended at the hands of Gunvolt. However, at the end of the countless battles, Gunvolt found himself unwillingly evolved to a new power beyond Septimas.
Shadow Yakumo, a secretive sister organization of the Sumeragi Group, eventually caught wind of the birth of this next-level power. Shadow Yakumo then ordered their battle priestess Kirin to stop Gunvolt’s awakening by sealing him with her Septima, Radiant Fetters.
"…You’ll be taking full responsibility for what’s about to occur."