Kikka reigns as King in Neo Kyoto, a city where supremacy hinges on victory in the card-based conflict, Build-Divide. Her rule anchors the societal order, underpinned by the pervasive belief that defeating the King grants any wish.

She is the younger sister of Teruto Kurabe, a truth unveiled only after her decisive victory over him in battle. This defeat shatters Teruto's spirit, draining his will to fight upon learning of Kikka's royal status. Three years later, Neo Kyoto lies in ruins. Hunted relentlessly by the KUGE, servants of the King who capture individuals to drain their magical power for the ruler's survival, Kikka is driven into hiding, severed from her Build-Divide deck.

Manipulated by Sakura Banka into forging the "Key" necessary to challenge the King, Teruto finds himself a pawn in Sakura's scheme. Sakura herself confronts Kikka, intending to win the battle and reclaim her physical body through the King's wish-granting power. Teruto then challenges his sister, declaring their duel a personal confrontation, not a formal Rebuild Battle. This clash reignites Teruto's suppressed memories, revealing the true nature of Neo Kyoto and the profound significance of the King's role.