A mysterious Bakugan player named Masquerade, who is ranked at #1 on the list of Bakugan players, is stealing Bakugan from players worldwide. Dan makes an open challenge to Masquerade, and loses two of his Bakugan to this mysterious player, thanks to a Doom Card, which makes a Bakugan disappear forever. Dan is lucky enough to not lose Drago, but might if he loses to Masquerade again.

Masquerade teams up with a player with Rikimaru, by giving him a very special Bakugan. When Rikimaru and Dan battle, Drago ends up using a dangerous move to save himself and win the battle. Dan gets angry, and throws Drago into a river, cursing the day they met.

Dan has a hard time adjusting to life without Drago. He ends up causing a schoolmate named Ryo to drop his computer and runs away, hurting Ryo's feelings. Masquerade takes advantage of Ryo's hurt feelings, and Ryo beats Dan in a battle. Dan finds Drago, and tries to make up with Ryo.

Dan and Runo meet for the first time, outside of the Bakugan website, and realize that they live in the same town. Dan drops his BakuPod, and Runo picks it up, noticing that Dan has battled Masquerade. She goes in his place, but ends up battling a boy named Tatsuya.

While at an amusement park, Dan and Runo are invited onstage to assist a magician act by two brothers. Dan picks a card, and realizes it's a Doom Card. The brothers are working for Masquerade, and Dan and Runo get tricked into a battle.

Marucho reveals that he secretly moved to Dan's neighborhood, and throws an elaborate welcome party. Masquerade makes a business offer with the famous pop band duo, Jenny and Jewels. The duo crash the welcome party, and challenge the Battle Brawlers.

Dan and Marucho fight against the pop star duo, Jenny & Jewels. After a narrow victory, Drago tells the Brawlers about how the Bakugan came to Earth, and how a human entered the Bakugan world of Vestroia.

Masquerade manipulates two boys, Kosuke and Takashi, into using his Doom Cards against the Bakugan Battle Brawlers. He promises that he'll reunite their friend Ai with her brother if they help him. Wanting to help their friend, they take the bait and soon run into Runo and Marucho, who are at the airport to pick up their website friend, Alice. Luckilly, Alice is skilled in the finer points of combination battle, and coaches her friends to victory. Alice has a secret, however, that might just ruin her friendship with the Brawlers.

Julie and her childhood friend, Billy, go one-on-one in a Bakugan battle. Although Julie's defeated by Billy, she's impressed with his skills and his Bakugan, "Cycloid." They make a great team, and Julie wishes she could befriend a talking Bakugan. Later, when Julie admits to herself how lonely she really is, the Bakugan Gorem appears. The two seem to be destined for each other.