A Book (本 hon) is a collection of sheets of paper bound together to hinge at one edge, containing printed or written material and/or pictures.
Books in Touhou
The main place where books can be round is the library of the Scarlet Devil Mansion, the largest library in Gensokyo. These books stay out of sunlight because they can be damaged over time. It's relatively unknown what kinds of books are in there. Hieda no Akyuu suggests that there are very rare magic books, and there are also many books from the Outside World. Certainly, unconfirmed to Akyuu, at least some books are in Esperanto, some were written by Patchouli and some are dangerous to even touch. Marisa Kirisame is known to steal books from here.
Patchouli Knowledge is usually shown to be holding a book, and she uses one in the fighter games, mainly to rack her opponent. Alice Margatroid also owns a book, called the Grimoire of Alice. In Chapter 2 of Curiosities of Lotus Asia, Tokiko was trying to read a book, but was beaten up by Reimu Hakurei. Renko Usami can also be seen holding a book.
Books can also be found at Suzunaan, a traditional Japanese style book renter located somewhere in the Human Village. Although it is a book lender, they also sell books, and even provide a small book printing service. Perfect Memento in Strict Sense, written by Hieda no Akyuu, was also printed and bound here. Most of the books they deal in are the books that drifted into Gensokyo from the Outside World, which they call "foreign books" (外来本 gairai bon). Kosuzu has been also secretly using some income of the store to gather a collection of rare demon books, and rents out at high price.
- Mystic Square
In Mystic Square, Alice Margatroid made use of the Grimoire of Alice in order to use ultimate magic against the heroine, having her the capability of being an Extra Stage boss. It proved to not be in good use however, since she was defeated.
- Embodiment of Scarlet Devil
Books appear as a stage enemy on Stage 4 of Embodiment of Scarlet Devil. It is not stated what these books are officially called. Before the midboss Koakuma appears, some magical books will emerge from nowhere and shoot circular, green danmaku. After the midboss, two books will appear on both sides of the screen, and shoot circular, blue bullets. This will happen a few times, but after, two books groups together will continue to appear and shoot more circular, green bullets, all while Fairy Maids and spinning enemies are also shooting at you. The higher the difficulty, the more bullets they'll shoot.
In the Extra Stage, books are seen supporting the midboss Patchouli in her last spell card Fire Water Wood Metal Earth Sign "Philosopher's Stone". After, some more books will appear and some do a fix sequence; some will shoot a number of circular bullets, some will sparkle a circular of bullets, some will do a 9-way of bullets and some will shoot directly at the heroine. Books will appear one at a time doing one of these events, where at the end a numerous amount of books will appear at once doing all these events, covering the screen with bullets.
The Scarlet Devil Mansion's library, containing books
Books in the spell card Fire Water Wood Metal Earth Sign "Philosopher's Stone"
The mansion's library, containing many books in Immaterial and Missing Power
Some books next to Patchouli in Perfect Memento in Strict Sense
Patchouli holding a book in Scarlet Weather Rhapsody
Patchouli's sigil in The Grimoire of Marisa is a book
Biting books in Inaba of the Moon and Inaba of the Earth