In The Witch and the Beast, grimoires are a kind of instrument that offers an individual witch-like powers.
Grimoires in The Witch and the Beast provide power and perform spells for whoever wields them.
In order to use the grimoires, no magical aptitude is needed. Just holding a grimoire gives an individual power that is almost on par with that of a witch.
The grimoires are a type of Forbidden Instrument which are taboo tools of dark magic. Lastly, either part of the grimoire can summon its other half instantly across space, but only up to a distance of roughly one kilometer.
This explains how Shulk and Loran were able to vanish instantly. Though the grimoires give one a lot of powers, there are some drawbacks to them.
The dark side of grimoires
When one gets hold of a grimoire, one must kill to feed it, as the grimoire will eat its user if they don’t give it sacrifices.
In Shulk and Loran’s case, they are using a two-volume grimoire called Sarnovasus. It requires the two of them to kill at least ten people in a day.
Ashaf tricks them by using dummies as cops. Hence, Shulk and Loran fail to meet their daily count of 10 bodies.
Though Shulk and Loran acquire witch-like powers, they don’t become as strong as Ashaf and Guideau. Hence, they are defeated quite easily.
Shulk and Loran claim that Keira brought the grimoires home, and that’s how they ended up touching the grimoires they have.
However, Keira doesn’t remember seeing them before. Ashaf explains that these Forbidden Instruments have wills of their own.
These instruments find the right person at the right time. Keira admits that Shulk and Loran were not the most well-behaved boys, but these grimoires did make them more evil.