The third Digimon series, which began airing on April 1, 2001, is set largely in a "real world" where the Adventure and Adventure 02 series are television shows, and where Digimon game merchandise (based on actual items) become key to providing power boosts to real Digimon which appear in that world. The plot revolves around three Tamers, Takato Matsuki, Rika Nonaka, and Henry Wong. It began with Takato creating his own Digimon partner by sliding a mysterious blue card through his card reader, which then became a D-Power. Guilmon takes form from Takato's sketchings of a new Digimon. (Tamers’ only human connection to the Adventure series is Ryo Akiyama, a character featured in some of the Digimon video games and who made an appearance in some occasions of the Adventure story-line.) Some of the changes in this series include the way the Digimon digivolve with the introduction of Biomerge-Digivolution and the way their "Digivices" work. In this series, the Tamers can slide game cards through their "Digivices" and give their Digimon partners certain advantages, as in the card game. This act is called "Digi-Modify" (Card Slash in the Japanese version). The same process was often used to Digivolve the Digimon, but as usual, emotions play a big part in the digivolving process. Unlike the two seasons before it and most of the seasons that followed, Digimon Tamers takes a darker and more realistic approach to its story featuring Digimon who do not reincarnate after their deaths and more complex character development in the original Japanese. The anime has become controversial over the decade, with debates about how appropriate this show actually is for its "target" audience, especially due to the Lovecraftian nature of the last arc. The English dub is more lighthearted dialogue-wise, though still not as much as previous series.

When did the third Digimon series begin?