One day Takato creates his own Digimon Guilmon when he slips a mysterious blue card he found in his deck through his hand-held card reading device, changing it into a D-Power (called a D-Arc in Japan), the Tamers’ version of a Digivice. The appearance and powers of his Digimon come from Takato’s sketches that were scanned into the device. Guilmon bio-emerges from the Digital World and is found by Takato. In his attempts to hide his new friend, Takato meets other Tamers Henry who met Terriermon in a computer game, and Rika whose success in card game tournaments caused many Digimon to come to her when she received her D-Power, and she chose Renamon, promising to make her stronger. Early in the series, the three Tamers and their Digimon duel foreign Digimon emerging into their world. Takato, Henry and their partners quickly become friends and allies, while Rika and Renamon prefer to fight on their own; however, they all soon realise that much more is at stake and the six unite. During their escapades, they encounter the michevious and mysterious Calumon, who has the power to make other Digimon digivolve, but dislikes fighting, and Impmon, a cruel Digimon that left his twin Tamers because he was sick of their bickering and selfishness, and thinks that all Digimon with Tamers are a disgrace. Along the way, the kids learn to be responsible for those creatures as a mysterious man known as Yamaki tries to stop wild Digimon from coming to the real world. From the secret government agency called Hypnos, Yamaki is in charge of monitoring and covering up Digimon activity around the globe.
When Yamaki attempts to use his project, the Juggernaut programme, to suck every Digimon back to the Digital World, a group of powerful Digimon calling themselves the Devas, who serve the Digimon Sovereigns, hijack the programme and begin to enter the Real World. The Devas believe that true Digimon should not pair up with humans, and they fight the trio of Tamers and their Digimon to defend their world against them. The Devas’ true purpose for entering the human world is eventually revealed; they wish to capture Calumon, and take him back to the Digital World, so that they can use his power of Digivolution. The Devas eventually succeed, although many are destroyed in the attempt. Impmon, meanwhile, is badly beaten by one of the Devas and is drawn back into the Digital World with the promise of power.