In the city of Neo Kyoto, one's social status is determined by their skill in a card game called Build Divide. The plot follows Teruto Kurabe, who, with the help of a mysterious girl named Sakura Banka, enters the "Rebuild" battle to complete a "Key" that will allow him to challenge the King. The rumor is that defeating the King grants any wish, which is Teruto's goal.

Set three years after the events of the first season and follows a changed Neo Kyoto that is in ruins. King's servants, KUGE, are stealing the magical power of the citizens, and the once-strong Kikka is now on the run and trying to survive without her Build-Divide deck. The season focuses on the fallout of the original series' conclusion, with a new story unfolding in the ruined city and the new antagonist, Mario Higuma, returning to cause more destruction.