Their city is in danger. Massive Kaiju are attacking, and no one knows why. The mechanized hero Gridman can stave off annihilation, and he's chosen Yuta Hibiki to help him. But Yuta's just a student, and even worse, he's lost his memories from before the Kaiju showed up. Heroism is necessary for survival, and with his friends at his back, Yuta has no choice but to fight - for everyone's sake.