Grimoire no Keiyakusha

is a Japanese light novel series written by Hideto Kido, with illustrations by Yugen. The series began publication on March 10, 2009 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
The girl Rizet, whom the ordinary high school student Souya Narutani met, was a summoner who used a "magic book" written about another world, Ilvalis.

Her job is to collect the "Grimoire" that was scattered all over the town in the accident. Souya signs a contract with Rizet's "Knight of the End" Alvarez, the genie of Rizet's "Spellbook", in order to save Rizet in crisis. The double-contracted "Spellbook" cannot be summoned unless Rizet and Souya are available.

In this way, Souya becomes a squirrel who collects "Spellbook" with Rizet ...