Babelonica Trail: Nishikasuga Gakuha no Tasogare

is the first volume of the Babelonica Trail light novel series, written by Choshiro Kaiba and Illustrated by Fuyuno Haruaki. It was released under the Dengeki Bunko Imprint in September 2014.

Synopsis
Research city, Nishikasuga city. Sakura Yaegaki, a beautiful childhood friend who came under the petiole who is also young while belonging to a school that repeats underground experiments. Does she bring the gospel or ruin?

(source: Dengeki Bunko Official Website - Translated)