The city of Tokyo is dominated by an ominous alien mothership, which appeared three years ago, sparking the greatest war in human history. The Japanese government's response to the "Invaders" led to mass production of weapons, causing controversy and pacifist movements. Despite the catastrophic circumstances, Kadode Koyama and Ouran Nakagawa continue to live their daily lives as normal high school students, unaware of the dark reality that awaits them. As they grow older, they begin to realize the true nature of adulthood in a world where the threat to humanity may not come from the Invaders, but from within.