Mysterious cards came down from the sky one day. Capable of summoning powerful creatures from another dimension, they became the centerpiece of a new game called Bakugan. The game gained instant popularity among children and teenagers, with the best of them competing in a worldwide ranking. Meanwhile, war for domination over Vestroia, the homeland of Bakugan cards, rages on. Invaded by the White Dragon Naga and his servants, the Doom Beings, the realm becomes increasingly destabilized. Dimensions begin to merge and many Bakugan players come to realize that their pastime is not merely a game. Danma Kuusou, one such Bakugan player, intends to become the World Ranking's leader someday. However, during one of his fights he experiences a vision of a clash in Vestroia. The fight suddenly moves to Earth, where Danma comes into possession of a talking, mighty fire Bakugan, Pyrus Dragonoid. He soon gets dragged into the conflict, and together with his Bakugan Brawlers team, must traverse the dimensions and restore balance in a ravaged world. [Written by MAL Rewrite]

After the invading dimensional monsters were beaten back, Seoul was rebuilt. This is the story of Closers in New Seoul. Mysterious dimensional gates opened all over the planet and unleashed a worldwide invasion of dimensional monsters. No monsters and tactics had any effect on the waves of dimensional monsters pouring out of the dimensional gates. City after city was mercilessly destroyed. But the opening of the dimensional gates did not only cause damage and destruction. The psychokinetic power that it awoke also enabled a tiny minority of humans to gain extraordinary psychic powers. With these psychic warriors, governments around the world were able to turn the tide of the war with these monsters. After unspeakable losses, the people of earth at least succeeded in closing the gates. Since they had closed the gates, these psychics began to be called "CLOSERS," and the invasion of the dimensional monsters was named the First Dimensional War. With the dimensional monsters vanquished, peace returned to the world, and the cities were rebuilt. Through dedicated research into the dimensional gates and psychokinetic power, humans learned that the gates open when there is a singularity in this mysterious power. However, their understanding of the gates was still incomplete. The CLOSERS who survived the First Dimensional War became part of an organization called UNION. Together, they researched the psychokinetic power in all over the world, working to prevent another dimensional war. And that's when the dimensional gates all over the world started shaking again - as ever stronger outbreed creatures renewed the attack on earth. (Source: Wikipedia)

Legend says that the enigmatic Millennium Puzzle will grant one wish to whoever deciphers its ancient secrets. Upon solving it, high school student Yuugi Mutou unleashes "another Yuugi," a peculiar presence contained inside. Now, whenever he is faced with a dilemma, this mysterious alter ego makes an appearance and aids him in his troubles. Wishing to unravel the mystery behind this strange spirit, Yuugi and his companions find themselves competing with several opponents in "Duel Monsters," a challenging card game used by people seeking to steal the Millennium Puzzle in a desperate attempt to harness the great power within. As the questions pile on, it is not long before they figure out that there is more than pride on the line in these duels. [Written by MAL Rewrite]