Nabari no Ou is a Japanese manga series written and illustrated by Yuhki Kamatani. It was serialized in Square Enix's shōnen manga magazine Monthly GFantasy from May 2004 to August 2010, with its chapters collected in 14 tankōbon volumes. In North America, it was licensed for English release by Yen Press. A 26-episode anime television series by J.C.Staff was broadcast in Japan on TV Tokyo from April to September 2008. In North America, the anime series was licensed by Funimation.

Gangan is a manga imprint owned by Square Enix Holdings. It originated as a manga imprint for Enix before the company re-branded as Square Enix. It publishes manga in several anthologies aimed at different reader demographic groups in the Japanese market. Its anthologies are home to some popular Square Enix manga series which were adapted into anime series, like Fullmetal Alchemist, Moribito: Guardian of the Spirit, Nabari no Ou, Inu x Boku SS, The Case Study of Vanitas and Soul Eater. The comics are later collected in paperback volumes under brand names such as Gangan Comics , Gangan Comics Joker and Young Gangan Comics , which identify the anthology of serialisation. These paperback brand names are formed by omitting any gekkan or shōnen in the magazine name and inserting Comics directly after the word Gangan.