- Bukku (ブック?) is the Japanese pronunciation of the English word "book".
Strengths and Weaknesses
This fruit grants the user the ability to control nearby books, regardless of their size, allowing them to telekinetically move them around and even use them as footholds.
The biggest strength of this fruit is the ability to trap living things inside a book's setting. This can be done in two ways. First, by hovering an open book above the target, they will be placed under the visual illusion that they are within the book's world, which will cease once the book is shut. Secondly, the user can physically trap targets inside a book, turning them into an illustration within that book, where they will not age; Mont-d'Or is usually seen pinning down his captives with oversized nails,  which are seemingly unbreakable. A person can travel in and out of a book at will by inserting a special bookmark into the page.
The user can also use books as a means of distant and broad communication. Mont-d'Or was shown calling multiple Den Den Mushi at once by connecting them all to a book, while he and his own Den Den Mushi were on top of another book. The specific mechanics of this ability are unknown.
Placing a target under the illusion of a book's setting only impairs their sight, allowing them to still move around and use other senses, as shown when Luffy was able to hear Nami and move around while under the illusion. Similarly, targets trapped inside a book can still communicate with the real world so long as the page they are on is kept open. Moreover, prisoners can be released by burning the books they are kept it, although this can be hazardous to them as well. Otherwise, the user is affected by the standard Devil Fruit weaknesses.
Mont-d'Or's most prominent use of his fruit lies in keeping Big Mom's collection of strange, rare creatures and beasts, as well as her prisoners, trapped inside oversized picture books, pinning them down with massive nails and storing them in a large library in Whole Cake Chateau. The regular library is used to store the strange creatures, while normal prisoners have a separate sections called the Prisoner Library. He also uses his fruit to coordinate the Big Mom Pirates, as seen during the pursuit of the Straw Hat Pirates, where he was seen connecting multiple Den Den Mushi to communicate with several of his crewmates at once.
In combat, Mont-d'Or controls normal-sized books as mid-air footholds to fly, and uses them to place foes under the illusions that they are inside the book's setting, leaving them distracted and open for attacks.
- "Hon" no Sekai ("本"の世界 "Hon" no Sekai?, literally meaning "World of "Books""): By hovering an open book above an enemy, Mont-d'Or traps them within the visual illusions that they are inside the book's setting, distracting and confusing them long enough for him or his allies to attack them. The illusion ends once the book is closed.
- This Devil Fruit is somewhat similar to Giolla's Ato Ato no Mi, as it lets the user to trap three-dimensional beings in a two-dimensional world.
- This Devil Fruit is somewhat similar to the non-canon Pasa Pasa no Mi, as they both revolve around books and paper except the Pasa Pasa no Mi can make paper but the Buku Buku no Mi cannot.
- Some of the species captured by Charlotte Mont-d'Or, and shown to the Vinsmoke Family by Big Mom in her library, are references to minor characters from Lewis Carroll's novel series Alice:
- One Piece Manga and Anime — Vol. 84 Chapter 846 (p. 4-7) and Episode 810, Mont-d'Or's powers are first seen.
- SBS One Piece Manga — Vol. 90 (p. 174), Mont-d'Or's Devil Fruit name revealed.
- One Piece Manga and Anime — Vol. 84 Chapter 847 (p. 4-6, 8-16) and Episodes 812–813.
- One Piece Manga and Anime — Vol. 85 Chapter 850 (p. 5-6) and Episodes 816–817.
- One Piece Manga and Anime — Vol. 84 Chapter 848 (p. 16-17) and Episode 814.
- One Piece Manga and Anime — Vol. 89 Chapter 899 (p. 2-4) and Episode 874.
- One Piece Manga and Anime — Vol. 85 Chapter 852 (p. 4-5) and Episode 819.
- One Piece Anime — Episode 854.