Digimon Zero Two Vol 1

From the Tokyopop edition

Three years after the defeat of Apocalymon, dark powers have risen again in DigiWorld in the form of a mysterious foe calling himself the "Digimon Emperor," who is out to enslave all of Digimon. Guided by previous members of the DigiDestined, a new team of kids must be trained to restore peace.

Source: OpenLibrary