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!