Tokoshie x Bullet: Kaijuu Gakuen

In 2030, the world's largest cities were destroyed by terrorists manipulating unidentified giant weapons. They called themselves "Tokoshie" and destroyed the city with overwhelming power … then disappeared. Twelve years later, in 2041, Tokyo. A transfer student appeared in front of Tsukimi, a high school boy who spends his days closed. From the day I met this boy who was somewhere away from the world, Tsukimi's "life-threatening school life for the survival of humankind" began!