It was announced at Yen Press' Comic-Con International panel in July 2008 that they acquired Oninagi for release in North America.

[3] The story begins with Nanami Kushimiya, an average 15-year-old schoolgirl excited about starting the new school year in hopes of getting closer to her crush, Kazuto Sanjouin.

When Nanami doesn't reveal a “true” form on the verge of being slain by Tomotaka's blade, Onigani, she believes she may have been wrong about her initial instincts.

Tsurugi, Kusabi, and Mori A group of demonic servants created by Princess Kinkan over 400 years ago.

In fact, their names represent that type of weapon they wield; Tsurugi (sword), Kusabi (wedge), and Mori (lance).

Hanged Man A selfish demon who went chasing after the power within Nanami behind the backs of his comrades once alerted of its presence.

Joy Kim of Mangalife.com criticized Volume 1 for being a book that is "basically supernatural action by the numbers", and that "The story also suffers from a somewhat scattered focus".

[6] Matthew Alexander of Mania.com also remarked on the book's lack of unique elements, but felt that "there is a large enough cast of characters from enough camps to make the story interesting".