Bundled with the 11th volume of Kanojo ga Flag wo Oraretara light novel.

Set in the land of Yuguto, the people thought that the land they live is the size of the world, but it's actually divided into several areas, each with a respective king. Even though there were small wars among areas, the kings had roundtable meetings to maintain peace and balance. It was until a dark group of dark monsters appeared... (Source: MAL News)

Kouji and his friends have defeated Dr. Hell and are now enjoying a break, but suddenly a strange prophet appears and warns everyone of an oncoming danger, mechanical beasts never seen before start appearing all around the world wrecking havoc. Its up to Kouji and his Mazinger Z to stand up to this threat but it seems he is vastly outnumber and outmatched.

This film served as an alternative link between the Mazinger Z TV series and the Great Mazinger TV series. It basically introduces Great Mazinger to the audience, as well as his enemies from the Mikene Empire.

Sendo Kazuki, failed the entrance exam for the art college he was applying to, His childhood friend, Kuhonbutsu Taishi forced Kazuki to enter the doujin (private publishing) world. (Source: AnimeNfo)