Tomorou Tenma possesses a uniquely potent e-Pulse—the energy generated by human thoughts and emotions that powers egg-shaped AI devices known as Sapotama. While daily life in the world depends on the assistance of Sapotamas, the intensity of Tomorou's e-Pulse frequently causes glitches within them. One night, a strange creature identifying itself as Gekkoumon emerges from his device and insists on consuming Tomorou's e-Pulse. Gekkoumon is a Digimon, a creature that feeds on e-Pulse and was born from an error in the Sapotama system. Some Digimon completely drain humans of their energy, leaving them in a comatose state called Cold Heart. When Tomorou's older brother, Asuka, falls victim to this phenomenon, Tomorou vows to avenge him. Tomorou encounters a group of Digimon-wielders named Glowing Dawn, who hunt down rogue Digimon for bounties. Their leader, Kyou Sawashiro, explains that there might still be hope for Asuka's recovery. Although Tomorou struggles to trust these strangers, he decides to join them, realizing that saving his brother may not be achievable on his own.