This movie shares the same story, music, characters and premise with Grendizer with few differences like the absence of totally different lead robot, the absence of Koji Kabuto and different character designs.
Despite being short, it's very fun to watch especially if you are fan of Grendizer and other Mazinger works and it's always interesting to see what could have been.
If you are interested in rare classics or if you are big fan of Go Nagai works, give this movie a watch
