A light novel is a genre of fiction in Japan, marketed mainly to younger readers, which are roughly analogous to young-adult novels in English-speaking territories. Many light novels serve as either the source material for many anime titles, and many anime are themselves adapted into light novels in the same way movie tie-ins are released for popular films.

The term “light” manifests in a number of different ways with light novels.

They’re light on the wallet, since most of them sell for 500 yen or less; light as reading, with a fast-moving story that wouldn’t run to more than fifty thousand words in English; and light on the eyes, with illustrations within the text every few dozen pages. To wit:

Presentation. Most light novels are published as “bunkobon”, a paperback format found primarily in Japan. The books are A6 sized – (4.1”×5.8” or 105×148mm)—and come wrapped in a color dustcover, which allows them to be carried around and treated a bit roughly (shoved into a pocket, stowed in a bag) without being banged up as easily as a conventional grocery-sized paperback might be. Bunkobon are also printed on paper whose quality ranges widely, from high-end acid-free paper to only a grade or two above newspaper.

Storytelling. Light novels are meant to be entertaining and fast-moving, and are written accordingly. They’re rarely more than three hundred pages, with paragraphs and sentences kept accordingly short. That said, many light novels are also installments in a series, since the format encourages a longer story to be broken up into many smaller chapters.

Some of those series can run amazingly long. The Guin Saga novels (inspiration for the TV series of the same name) ran to over one hundred twenty books released over the course of thirty years, before the death of author Kaoru Kurimoto. Rental Magica was adapted from a few of the novels in a series that at the time (2007) had twenty-plus volumes released since 2004.

Illustrations. The vast majority of light novels sport illustrations of the action, usually ten or so scattered throughout the body of the book. In cases where a light novel is the inspiration for an anime, and the anime’s look is patterned after the illustrations, the illustrator is given character design credit (e.g., the artist take for Katanagatari, or pakofor Rental Magica).

All these factors—ease and speed of reading, serialized installments, graphic elements—all help make them candidates for anime adaptations. The sheer popularity of a given light novel series is the main instigator, though: once a series accrues a big enough fanbase or a large enough number of installments, it’s almost certain to be made into an anime.

The current general format for light novels first started to come to prominence in the Seventies, with the aforementioned Guin Saga being a staple example. In the following decade, Haruka Takachiho’s comic sci-fi stories (under the general rubric of The Dirty Pair), along with Hideyuki Kikuchi’s Vampire Hunter D, were among the first to be adapted in major, prominent anime productions. Easily the biggest and most ambitious light-novel-to-anime production that started during that time was Legend of the Galactic Heroes, a ten-volume space-opera epic by Yoshiki Tanaka, which made the jump to anime over a period of ten years from 1988 to 1997. (The anime remains famous amongst fans for not having a legitimate English-language release.)

Light novels continue to remain a strong source for anime projects that find audiences both at home in Japan and abroad. The fact that a given anime’s source novel is not available in English (Baccano!, D.Gray Man, Record of Lodoss War, The Story of Saiunkoku) generally doesn’t hurt the anime’s chances of being licensed domestically or enjoying success. That said, some light novel series translated to anime are lucky enough to also have some of their source novels published in English as well. Among them:

• .hack
• Boogiepop Phantom
• Gosick
• Guin Saga. Sadly, only the first five were published in English; sales did not justify further installments.
• Gundam
• The Haruhi Suzumiya series (shown here; ), which has spawned an overseas fanbase as fervent as its domestic one.
• Karin (aka Chibi Vampire)
• Kino’s Journey. Its English-language light novel release was marred by editorial interference on the part of its publisher, Tokyopop, which insisted on re-ordering chapters against the wishes of the author, Keiichi Sigsawa. This edition is now out of print due to the publisher also being defunct.
• Moribito: Guardian of the Spirit, although only the first two books were released in English.
• Scrapped Princess
• Slayers
• Spice and Wolf
• Trinity Blood
• The Twelve Kingdoms
• Vampire Hunter D. Dark Horse Publishing has committed to bringing out the entire series, which is still ongoing in Japan as well.

The economics of publishing light novels in English tends to make it difficult to justify translating them. Most of them sell too few copies to make the project viable. In a few cases (e.g., Haruhi Suzumiya), savvy marketing allowed the book to find an audience outside of existing fans for the show, and thus justify more installments being translated.