Improper Capture Method of Classmates & Labyrinth

Nishi High is set to close in two years, leaving only seven students, including Hazakura Motoya. He plans to stay until graduation, enjoying the chance to finish high school without much effort. The quiet school is soon unsettled by the arrival of three transfer students: Kayama, Mizumura, and Toujou, who are members of a special military division. Not long after, a giant tower suddenly appears on the school grounds. Motoya and the three girls witness its arrival, and Motoya is chosen to enter the tower alongside them and uncover its mysteries.