Great Mazinger tai Getter Robo

A strange craft releases the metal-devouring monster Gilgilgan near Japan, forcing Great Mazinger and Getter Robo into the same crisis. Their pilots initially treat one another as rivals, and their lack of coordination allows the creature to feed, evolve, and become an even greater threat.

Realizing that neither machine can win alone, the two teams set aside their pride and devise a joint assault. By drawing Gilgilgan away from populated areas, they prepare a decisive battle that tests the combined power of both legendary robots.