Occupation of Heimdallr
Zoro-Agruga occupied Heimdallr from S.371 to ca. S.470 and, with the dark breath it sprayed, turned the capital into the city of the dead. Zoro-Agruga's reign ended with the counter-attack of the Imperial family, led by Emperor Hector I, wielding the Vermillion Divine Knight Testa-Rossa. Upon its death, its blood claimed Hector's life and placed a curse on the Divine Knight.
Its remains were locked away below the newly built Heimdallr.
Reanimation through artifact
In S.1204, Zoro-Agruga's carcass was brought back to life by Michael Gideon of the Imperial Liberation Front, through the means of an artifact shaped like a flute, referred to as the Demonic Flute. Class VII managed to hold off Zoro-Agruga until Gideon's flute was destroyed and the dragon's remains returned to their eternal slumber once again.
The Dark Dragon's Revival
Zoro-Agruga is encountered and fought in his sanctuary which appears underneath the Imperial Museum. With the assistance of Roselia he is defeated.