Oninagi

From Yen Press:

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?