In the metropolis of Heartland, a young boy named Yuuma Tsukumo dreams of the same goal that fills his classmates" hearts: earning the title of the greatest duelist. Yet, because his fighting skills are weak and unpolished, that ambition feels out of reach. The turning point comes when the school bully, Ryouga "Shark" Kamishiro, takes the key his father had passed down to Yuuma and splits it into two shards, unknowingly propelling the boy toward his dream.
Yuuma keeps one shard and challenges Shark to a duel, but he quickly realizes that his inexperience cannot match the bully"s prowess. In an instant, the broken key repairs itself and a "Door of Destiny" opens before him. Using the key, Yuuma steps through and is greeted by an alien named Astral—a being visible only to him, who claims to be a guardian of memories.
The bewildered Yuuma learns that his recollections have been divided into 100 "Number Cards," each holding a fragment of his past. He must gather them, yet others seek the same cards. Faced with these revelations, Yuuma and Astral must defend Heartland City from looming threats that could unravel reality itself, regardless of any divine intervention.
Studio Gallop Japan