Betsumon are these lanky, weird Digimon that hang out in packs wearing Gatomon bodysuits. They're way more dangerous than they look—they specialize in impersonating other Digimon or humans, stealing their identities and replacing them so completely that the original person just stops existing. The creepy part is that even though the Betsumon look and act nothing like whoever they're pretending to be, everyone around them will recognize the fake as the real deal. They don't even need to have met them or made eye contact. Eventually the victim just vanishes entirely, and since they're erased from existence, they don't even leave behind a Digi-Egg. The Betsumon tend to be pretty smug about pulling off the switch, and they'll chuckle even when they lose.
One episode opens with a Betsumon already disguised as Jellymon after ambushing her while she was running errands. Another one corners Hiro's partner Gammamon while he's heading to meet his new friend Gotsumon and manages to slip into the dorm undetected. At first Hiro still knows his own partner, but once the pack leader tricks Gammamon out and takes his place, even Hiro stops recognizing him—and so does everyone else. Clockmon can't identify him, Ruli and Angoramon can't recognize him over video chat, and Kiyoshiro doesn't even notice despite having never seen the fake before. Completely disoriented, Gammamon runs into another victim, Meicoomon, who vanishes right after explaining what happened to him. That night, Gammamon watches in horror as about twenty Betsumon swarm the whole dormitory, methodically stealing everyone's identities.
The next day, Hiro invites both Gammamon and the imposter to a picnic and pours out chocolate snacks for them. Gammamon scarfs his down instantly, but the Betsumon can't eat that much without breaking character—snapping Hiro back to reality. The pack attacks, and Gammamon digivolves into WezenGammamon, though his Sedna attack doesn't do much damage since they're Ultimate-level. They smack him into the sky, but WezenGammamon digivolves again into Canoweissmon and wipes out the entire swarm in one shot. Clockmon locks them all up afterward.
Later on, when Kiyoshiro ends up in a coma after getting hit by a truck controlled by Sepikmon, a Betsumon disguised as a hospital nurse reveals itself—Clockmon had sent it to bring Kiyoshiro to Mummymon. It makes clear that it's only helping because Clockmon ordered it to.
Content compiled by AnimeList.moe from publicly available sources.
