Digimon Tamers: Brave Tamer

Story
Brave Tamer follows the cliffhanger ending of D-1 Tamers where Ryo and Millenniumon take a trip through time to, supposedly, the future. However, something went wrong and Ryo was catapulted into the past, where he met Monodramon, his partner later on. It is revealed that all Digital Worlds were created by the computer Atanasoff, the world's first Digital Computer upon his activation in the 1940s through support with ENIAC, the second computer to be activated, and that the Digital Worlds diverged into alternate realities overtime.

Ryo seeks the aid of fellow Tamers and Digidestined to help to defeat ZeedMillenniumon. He does so with ENIAC's aid, though how ENIAC is able to traverse time and different realities is unknown. He has to save the Tamer/Digidestined from the threat they are currently facing before they will give him their Digimon as thanks, just like during Anode Tamer. Ryo will alternatively save Tamers/Digidestined while fending off Digimon that ZeedMillenniumon has sent to take over ENIAC's world. Millenniumon has also made clones of the Digimon Kaiser/Emperor and the respective leaders of Adventure, Adventure 02 and Tamers. It is believed that Ken in the Millenniumon's future had betrayed his friends thanks to the Dark Spores that Millenniumon planted in Tag Tamers. It is hinted by the game as some of the Boss Digimon Ryo battles are Armor Digivolutions of Wormmon. In one of the talks between Monodramon, Ryo and ENIAC, it is revealed that Millenniumon does so so as to gain control of all realities and rid the future of the resistance he currently faces.

Ryo eventually confronts Millenniummon at the future, as ENIAC's last ditch attempt to save the world before Millenniumon can take over it. Ryo learns then that Millenniumon is in fact his true partner. Monodramon and Millenniumon dispute over who shall remain Ryo's partner until the small dragon forces a jogress between himself and Millenniummon, after weakening the latter severely, resulting in a Digitama (or DigiEgg) that will one day hatch and digivolve into Cyberdramon.

In the end, Ryo was given the option to either return to his world (Adventure) or go to the world of the Tamers. He chose to go to the Tamer's world, for reasons unknown. It is unknown how he got his parents to the Tamer's world as well. It is possible that they were only adopted parents or that they were already part of that world. If so, it is unknown what happened to the Ryo of that world.