What world is this?

In a war-torn world where colossal giants threaten the survival of humanity, Kayiakura and Akaiala face the harsh reality of an unrelenting conflict. When tragedy strikes Akaiala’s life with the death of his brother Ishidaki, young Kayiakura is forced to confront death and pain. As war continues to ravage everything around him, the arrival of the Injusther League, a mysterious force of hunters with advanced equipment, reveals that the future of humanity depends on the courage and strength of those who choose to fight. Kayiakura now understands that to protect the ones he loves and secure a future without war, he will need to become stronger, much stronger.