The Aequivalentis Grimoire is a Grimoire in the shape of traditional balancing scales. When something is presented to it, the Grimoire will take or give something that is the equivalent of that gift.
An onigiri made by Noel Vermillion fell onto the Grimoire, and its equivalent to take was Mai Natsume's memories. They eventually returned, and Estella McKenzie took the Grimoire into safekeeping, placing a sealing Ars Magus over it. [1] Noel stole the Grimoire not long afterwards, using it to help create clean laundry with the Team Remix Heart in order to pass one of the three tests set by the Aedsqui Grimoire. [2]