Much to the horror of Meiko Mochizuki, her Digimon partner Meicoomon is forced to evolve into Meicrackmon and falls under an evil influence in the process. As Meicrackmon disappears to wreak havoc elsewhere, it seems that the Digital World itself starts to reject the presence of Meiko and the other Chosen Children. While evading various enemies who come after them, the group attempts to find their way back home. In the human world, a messenger from the mysterious entity Homeostasis visits both Meiko's father and Daigo Nishijima of the Incorporated Administrative Agency to discuss Meicoomon's origins. The messenger informs the two that Homeostasis plans to eliminate the digital monster. By doing so, they hope to prevent further Digimon from materializing in the human realm—regardless of the Chosen Children's feelings on the matter.

The Chosen Children are in shock after the betrayal of Meicoomon, the digital monster who had recently joined their group alongside her human partner, Meiko Mochizuki. Koushirou Izumi is determined to diagnose the infection that took control of Meicoomon. Meanwhile, Takeru Takaishi realizes that his own partner, Patamon, is starting to exhibit alarming symptoms similar to those of other infected Digimon, like Meicoomon. Just then, the Chosen Children receive a message from the mysterious entity Homeostasis, who informs them that their world is in danger of total destruction—and the Digital World, the home of the Digimon, is too. Homeostasis plans to enact a Reboot, which will reset all the data that makes up the Digital World and eradicate the infection. However, the Reboot will also erase the memories of all Digimon, including the Children's partners. Can the Chosen Children stop Meicoomon before the Reboot becomes necessary, or is this the end of their time together with their Digimon?

Sequel series to Kodai Oja Kyoryu King. The Alpha Gang and the Ancients return. While the parents are talking, they are kidnapped by Gunenco, a member of the Zanjark Space Aliens. This causes the Alpha Gang and D-Team to join forces against the Zanjark Space Aliens in their plot to obtain the Cosmos Stones. Seth later returns as an ally to the Zanjark space aliens. Jark, the leader of the Zanjark, provides the dinosaur cards

Kei and Yuri were originally junior auxiliary agents in the Worlds Works and Welfare Agency (W.W.W.A. or 3WA for short) when the two were paired together under the codename Lovely Angels. Kei was coming off her fourth probation for something she had done, and Yuri's dating exploits were common knowledge, not to mention the two had an instant dislike for each other when they met. At first, Kei and Yuri refused to work with each other, and Kei even resigned from the 3WA. Afterwards, the two continued to work together, although they earned their nickname, the Dirty Pair because of all the collateral damage the two (unintentionally) cause in the completion of their cases. And even though the two now get along with one another, they continue to bicker and complain to each other. Although it is often said that these are younger versions of the original Lovely Angels Kei and Yuri, in truth this series is an alternate universe telling of Dirty Pair, set in the years 2248-49. (Source: Wikipedia)