Tensou no Shita no Basilace (1) Marebito no Hitsugi I

is the first volume of the Tensou no Shita no Basilace light novel series, written by Kohei Ito and Illustrated by Yuchi Izumi. It was released under the Dengeki Bunko Imprint in October 2004.

Synopsis
"Towers" and giant creatures that suddenly appeared all over the world. Due to its existence, Japan was divided into east and west across a vast no-man's land. In 2018, 15-year-old Atsushi Kawanakajima, who was in eastern Japan, was selected by the military observation team and aims to become a "tower". However, the corps led by him was wiped out "as originally planned". Only Atsuki escaped to South Hyogo, a remote area in the eastern part of western Japan. Atsushi started working as a member of the disaster prevention team while attending school in the land where the standard of living of the citizens had declined until the 1960s. To play a part in the battle for the resurrection of humanity with his classmates. In the first half of "Marebito's Coffin" published in "Dengeki hp" magazine, two newly written volumes have been added, and a new series has finally started.

(source: Amazon JP - Translated)