Owari no Chronicle

Sixty years prior to the outbreak of World War II, humanity discovered ten parallel worlds that existed under distinct physical laws. The force sustaining these alternate worlds is referred to as Concept. Concurrently, it was found that all these parallel worlds were on a collision course, with those lacking the most Concept slated for annihilation. To ensure its survival, the world known as Low-G, devoid of its own positive Concepts, initiated the Concept War to secure the most Concepts. It plundered the positive Concepts of the other worlds, referred to as Gs, leaving only Low-G intact. Sixty years have elapsed, and the present day finds Low-G on the precipice of destruction due to the rapid expansion of its negative Concepts. In an effort to rectify this situation, Low-G requires positive Concepts from the remaining alternate worlds. UCAT, the team responsible for the devastation of the parallel worlds sixty years prior, has formed Team Leviathan to establish communication with the survivors from the other worlds. Mikoto Sayama, the protagonist of this tale, has been thrust into a position of negotiation following the passing of his grandfather, a key figure in the Concept War and the negotiation team. With the weight of his family name, "The Sayama family name is villain itself," and the accumulated hatred, young Mikoto embarks on a perilous negotiation with the other worlds.