After two years searching for his missing parents, Y/N Tsukamo returns home to Heartland City. But the world he knew has changed. Mysterious 'Number cards' and the formidable Barian threat emerge, drawing his younger brother Yuma into a dangerous conflict. Now, Y/N must navigate treacherous duels and hidden truths, his own past intertwined with the fate of two worlds. Can he protect his brother and uncover the secrets of the Numbers before both realms are lost?