Barrier Cracker Kami no Tate no Hikari to Kage

is the first volume of the Barrier Cracker light novel series, written by Kyonosuke Seki and Illustrated by KeG. It was released under the Dengeki Bunko Imprint in August 2015.

Synopsis
Aigis, an invisible shield that protects people from all kinds of wounds and illnesses. Benefiting from that, the millennial city of Armoroth enjoyed peace and prosperity. However, there is a murder that shakes the order of the world, which cannot happen there. While whispering the existence of a person who crushes Aigis (barrier cracker), Inquisitor Belhelmina pursues the mystery of the case with the information shop Kurikara. A girl accused of heresy, an old pope hoping for immortality, and all the key apocalypse ... What is the astonishing truth behind various clues !?

(source: Dengeki Bunko Official Website - Translated)