Mazinger Edition Z: The Impact!

In 1972, the Apollo 17 mission discovered a hypergate to Mars on the surface of the moon. Soon a war breaks out between Earth and Mars, and Martian soldiers begin to descend from the sky, riding steel giants, intent on exterminating humanity.

Year Seven of the Kowa Period, in the former Hokkaido Block, live brothers known as the Nameless Mercenaries. The Emperor, Callis al Britannia, tries to plunge the world into chaos with the help of his servant, Norland, and his Einberg Knights. Rozé and Ash take action from the Northern lands.

An alien race called Gauna has destroyed Earth. leaving humanity struggling to survive aboard the spaceship Sidonia. Even though it’s been a century since the last encounter with the Gauna, military service is mandatory. For Nagate Tanikaze, whose grandfather secretly hid him in the forgotten bowels of Sidonia, it’s a strange new world as he’s forced to come to the surface. Yet his recruitment comes just in time, for the Gauna have suddenly reappeared.

In the near future, humanity has taken its first steps towards journeying into the far reaches of the galaxy. Upon doing so they discover a huge race of insectoid aliens known as "Space Monsters." These aliens seem dedicated to the eradication of mankind as they near closer and closer to discovering Earth. In response, humanity develops giant fighting robots piloted by hand-picked youth from around the world. Shortly after the discovery of the aliens, Noriko Takaya, the daughter of a famous deceased space captain, enters a training school despite her questionable talents as a pilot. There, she meets her polar opposite, the beautiful and talented Kazumi Amano, and is unexpectedly made to work together with her as they attempt to overcome the trauma of war as well as their own emotions.