Light Novel
A light novel is a Japanese prose novel for teenage and young adult readers, illustrated with manga-style art, often the source of later manga and anime adaptations.
Where the word comes from
A wasei-eigo coinage, "light" plus "novel" (raito noberu), used in Japan from around 1990 for short, accessible genre fiction.
In depth
Light novels are paperback novels, usually around two hundred to three hundred pages, written in an accessible style with plenty of dialogue and illustrated with a colour cover, colour inserts and several black-and-white pictures in the manga style. They are published in numbered volumes, like manga.
Where they come from
Many begin as web novels posted on sites such as Shōsetsuka ni Narō before a publisher picks them up. Successful light novels are often adapted into manga and anime, which is how most English-speaking readers discover them. Isekai stories in particular are dominated by light-novel originals.
On the shelf
English publishers issue light novels alongside their manga, and bookshops shelve them together. A series can exist in three forms at once — light novel, manga adaptation and anime — with the light novel usually furthest ahead in the story.
Where it appears
Sword Art Online by Reki Kawahara. a light-novel series that became a global franchise
Spice and Wolf by Isuna Hasekura. light novel later adapted into manga and anime
What it means today
If you finished an anime adaptation and want to know what happens next, the light novel is usually the original source and the furthest ahead.