On an otherwise calm day, the sky suddenly tore open, releasing extradimensional beings called the Unknown that immediately and mercilessly attacked humanity. To protect the future, all Japanese children were placed into cryogenic stasis until the war could be won.
Years later, with humanity holding a foothold in a part of Japan that had become the frontlines, the children were revived. While in their frozen state, each had developed unique supernatural powers known as Worlds. The six most powerful individuals were tasked with commanding the reclaimed cities, using their abilities to defend against the unending invasion. Among them were childhood friends Ichiya Suzaku and Canaria Utara, who governed Tokyo; siblings Kasumi and Asuha Chigusa, who managed Chiba; and Maihime Tenkawa and Hotaru Rindou, who oversaw Kanagawa.
As routine attacks from the Unknown continued and personal conflicts between the city leaders and their deputies grew, petty rivalries emerged, causing frequent disputes among the three cities. When the Unknown abruptly increased their offensive, the leaders of Tokyo, Chiba, and Kanagawa must unite or face the loss of the last bastion protecting humanity from extinction.
