Arbatel

Arbatel is a mysterious Grimoire created with magic by unknown backgrounds. With the information she has absorbed from the real world, she has become a rom-com otaku with a obsessive desire to create the perfect rom-com world. The Grimoire Arbatel is the main antagonist of Volume 18 as she absorbs the consciousness of Kimihito, his household girls, and numerous other people in order to take them into her world and brainwash them into believing that they are students of Grimoire High School.

To blend in with the crowd of people in the Grimoire, Arbatel changed her form and took on the identity of Honma Shiori, a member of the school's library committee.

History
Much about Arbatel's past and origins is largely unknown, but according to Ms Smith, a Grimoire was originally just a normal book that was altered by the magic that imbued it and is now a kind of Liminal. Given this, it is possible that Arbatel was originally a book owned or made by a wizard, although this is unconfirmed.

The Grimoire, through unknown circumstances, ended up in the possession of the Kayado Public Library in Japan, where it was housed in a section containing only school-themed romantic comedy manga. By absorbing the information from the manga, Arbatel developed a great fondness for rom-coms, although at the same time she also harbored a strong dislike for harem rom-coms. However, just reading the manga made Arbatel not a rom-com fan, but a rom-com Otaku, which meant that she only wanted to be around love couples to see their little moment of love between them. Arbatel had no desire to experience a romantic comedy herself.

Arbatel eventually came up with the plan to create the perfect school-themed rom-com world, the world of Grimoire High School. Somehow Arbatel found out about Kimihito, and due to the fact that he was living with seven Liminal girls but couldn't get into a committed relationship with any of them, Arbatel quickly developed a strong dislike for him. She considers him a "harem rom-com protagonist" and on occasion planned to absorb his consciousness to bring him into her world to change his "filthy harem obsessed heart".

Plot
After Arbatel created the world of Grimoire High school, just prior to the events of Chapter 74, Arbatel began absorbing the consciousnesses of humans and Liminals reading the book. When a person read the Grimoire, their body fainted while their consciousness was absorbed into the magical world of the school. The enchanted Seifukus brainwashed the "students" into believing that they were actually students at the school. However, since Arbatel also cared for the well-being of the people, the Grimoire always used her magic to summon an ambulance, which took the unconscious people to a hospital for their own safety.

Of course, the series of people fainting en mass didn't go unnoticed for long and was also reported on the Japanese morning news. After secret investigations lead to Arbatel being responsible, Ms Smith hires the girls from the MON to remove the Grimoire from the Kayado Public Library and take it into custody. However, this plan backfires when Arbatel secretly sets a trap for the MON-team by disguising itself to look like a normal manga. And when Zombina finally opens the book in an inattentive moment, Arbatel absorbed the consciousnesses of the four MON girls as well.

Zoological Classification
A Grimoire was originally just a normal book, but due to the magic that has been imbued into it, it is now some kind of living being or Liminal, although it is difficult to define whether the book is truly "alive". A Grimoire absorbs information from its environment through unknown mechanisms, and then used that information to affect its environment through magic. Grimoires possess a variety of abilities, such as absorbing the consciousness of people reading them and then trapping them in a fake magical world created by the Grimoire itself. This makes a Grimoire potentially dangerous, but also one of the most mysterious Liminals.

Trivia

 * Arbatel is the first Liminal in the series that can be viewed as both a living being and an object.