Upon meeting for the first time, undefeated street fighter Marcus Damon and renegade Digimon Agumon become friends in the most natural way possible for the knuckleheaded duo—by fighting their hearts out. The self-proclaimed "ultimate team" are recruited by a secret government organization called the Digimon Data Squad, or DATS, who had witnessed an unbelievable human fighting blow for blow with a Digimon. Their primary objective is investigating mysterious problems caused by Digimon entering the real world, and the world is currently in the midst of a crisis with Digimon appearing at an unprecedented rate. Embarking on various missions with DATS, Marcus and Agumon become colleagues with adolescent genius Thomas H. Norstein and his Digimon partner Gaoman, along with the kind-hearted Yoshino "Yoshi" Fujeda and her Digimon partner Lalamon. As the group continues to investigate the rapid increase of Digimon in their world, a darker truth begins to surface, and it is up to Marcus, Agumon, and their friends to get to the bottom of things. [Written by MAL Rewrite]

The Digital World is in a state of war, with the evil Bagra Army attempting to collect fragments of the Code Crown. Whoever manages to collect all 108 fragments will become king of the Digital World. An evil group of Digimon, known as the Bagra Army, are determined to get their hands on the Code Crown. Digimon Xros Wars features Taiki Kudou, a soccer-loving middle schooler who will always go out of his way to help people in need. When out with his friends Akari Hinomoto and Zenjirou Tsurugi one day, he hears a voice calling out for help. Investigating the situation, he meets a Digimon named Shoutmon who has been severely wounded in a nearby alley. Using the power of a strange device called a Xros Loader, Taiki manages to save Shoutmon's life, but is pulled into the Digital World alongside Akari and Zenjirou. Determined not to let the evil Bagra have their way, Taiki and his friends join with Shoutmon and other local Digimon to form their own army known as Xros Heart. Now Xros Heart must fight their way across the Digital World to collect Code Crown fragments and defeat the Bagra Army, but Taiki and his friends are not the only humans caught up in this war of monsters…

Returning to the Digital World, Taiki and Shoutmon learn that the Bagra Army has taken it over and reformatted the world to have Seven Kingdoms, each ruled by a general. (Source: AniDB)

Digimon Xros Wars: Toki wo Kakeru Shounen Hunter-tachi takes place one year after the defeat of Bagramon and company. Since then, Taiki Kudou and Yuu Amano have formed a basketball team with Yuu’s classmate, Tagiru Akashi. One day, Tagiru discovers a strange area called the DigiQuartz, a strange and unstable realm that exists between the human and digital worlds. He then realises that children all over the world have obtained Xros Loaders as well as Digimon partners to participate in a competition called the 'Digimon Hunt'. Digimon that wander from the digital world into the DigiQuartz are able to feed off of what negative emotions leak in from the human world. This makes the Digimon stronger at the expense of being extremely violent. As a result, the Digimon Hunters must work to stop these Digimon from wreaking havoc in the human world. Joined by the troublemaking Gumdramon, Tagiru aims to become the top Digimon Hunter, all the while unaware of Taiki and Yuu’s previous Digimon connections. Yet a sinister force lurks with the creation of the DigiQuartz, and the young Hunters will soon realize that the Digimon Hunt is much more than a simple game...