Oninagi

is a japanese manga series written by Ishida Akira. It began serialisation in the Vol. 1 special edition of Manga Time Kirara Forward.

The series was released under 4 volumes from September 2007 to May 2010. The series was also released in english by Yen Press from April 2008 to October 2014.

Synopsis
Average schoolgirl Nanami is excited about only one thing — getting closer to her crush during the new school year. Little does she know that there’s an ancient power running through her veins, which is why she’s being pursued by Tomotaka Onigoroshi, a swordswoman who will stop at nothing to rid the world of Nanami’s presence! But while their initial confrontation is as hunter and quarry, will Tomotaka’s allegiances shift when Nanami steps up to defend her against an unexpected opponent?

(Source: Yen Press)