Zessei Shoujo Defensol (Volume)

is the first volume of the Zessei Shoujo Defensol light novel series, written by Maki Masato and Illustrated by Kazuyuki Yoshizumi. It was released under the Dengeki Bunko Imprint in December 2005.

Synopsis
"Suddenly, you become my" King "," Shin Hatachi makes an unexpected confession to Yuina Amane, who transferred to school a month ago. She calls herself "Boundary Guardian " and wants her to be her own "King " ... With that as a trigger, an incident comes in peaceful days. A mysterious group called "Tenjo Gekidan ", a duo of black and crimson who suddenly attacks. What is the King of the Gate, what is the Boundary Guardian, and what is the enemy "Daybreak" coming from a different area? The hot and runaway three days of July are about to begin.

(source: Bookwalker JP - Translated)