Masaru, is a second year Junior High student, and is undefeated in battle, He meets the Digital Monster Agumon, who has escaped from DATS, a secret government organization. Despite terrible first impressions, the two become best friends by talking with their fists. With others, Masaru and Agumon work to investigate various incidents involving the Digital World and Digital Monsters, to try and get to the bottom of things.

Source: ANN

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Same setting: Digimon Adventure
Side story: Digimon Savers The Movie: Kyuukyoku Power! Burst Mode Hatsudou!!
Other: Digimon Savers 3D: Digital World Kiki Ippatsu!