Shisou Toshokan no Livre Blanche IV

is the fourth volume of the Shisou Toshokan no Livre Blanche light novel series, written by Yoshino Origuchi and Illustrated by KeG. It was released under the Dengeki Bunko Imprint in October 2011.

Synopsis
Mr. Itsuki, something has happened to the Death Hearing Concert Hall. Jumo Bull, one of the twin caretakers, is missing. A mysterious series of injuries broke out in the vicinity, and it seems that caution is required. We propose to invade the student president of Itsuki-sama's school, Yukari Midorigaoka, who will hold the key to disappearance. ……Okay? You're right, Mr. Itsuki. This costume is a race queen. It has nothing to do with this incident, but what happened to it?

(source: Bookwalker JP - Translated)