Upon meeting for the first time, undefeated street fighter Masaru Daimon and renegade Digimon Agumon become friends in the most natural way possible for the knuckleheaded duo—by fighting their hearts out. The self-proclaimed "ultimate team" are recruited by a secret government organization called the Digital Accident Tactics Squad, or DATS, who had witnessed the unbelievable spectacle of a human fighting blow for blow with a Digimon. Their primary objective is investigating mysterious problems caused by Digimon entering the real world, and the world is currently in the midst of a crisis with Digimon appearing at an unprecedented rate.

Embarking on various missions with DATS, Masaru and Agumon become colleagues with adolescent genius Touma Norstein and his Digimon partner Gaomon, along with the kind-hearted Yoshino "Yoshi" Fujieda and her Digimon partner Lalamon. As the group continues to investigate the rapid increase of Digimon in their world, a darker truth begins to surface.