Digimon: Digital Monsters

Ken finds a woman in his room who knows his past. While helping in the restoration, Davis, Kari and T.K. find that their Digimon can't Digivolve naturally despite the Control Spires being deactivated. Cody is attacked by Thundermon, leading to Armadillomon to Digivolve into Ankylomon. Thundermon is killed by Ken and Stingmon, leading the DigiDestined to become wary of him.