An alien-like Digimon who lives under a mountain in the Server Continent. He has a Pocket Dimension of his own under the ground to trap peasants and tricks them by threatening to send them to Hell if they don't release their curiosity from their minds so he can collect them. Izzy and Tentomon fall after DemiDevimon guides them with warnings spread all over the road. Izzy falls under his trap and releases his curious mind for Vademon, remaining brainwashed. Meanwhile DemiDevimon pleads Vademon with false promises to steal Izzy's Crest of Knowledge, but Izzy regains his mind thanks to Tentomon. Vademon fights against Kabuterimon but his powerful Ultimate level forces the giant beetle to digivolve to MegaKabuterimon for the first time and defeats him.