The film is commemorating the 45th anniversary of the original Mazinger Z manga and television anime series.
Both manga are spinoff works of the new Gekijōban Mazinger Z / Infinity (Mazinger Z: Infinity) anime film based on Nagai’s Mazinger Z manga.
Nagai launched the Mazinger Z manga in Shueisha’s Weekly Shonen Jump magazine in 1972, and the television anime series premiered at the same time.
The manga shows new portrayals of events from the story of the original Mazinger Z manga, such as Kōji’s first time seeing Mazinger Z, his relationship with Sayaka, and the battles with Baron Ashura and Dr. Hell.