Heartbeat (Naruto FF) Book 1: Her Frozen Heart

Rin is a truly special girl.

She was blessed with the face of an angel, but was cursed with the soul of the devil. She was blessed with a body that women would kill for, but cursed with scars that appeared out of no-where. She was blessed with luck that gave her riches, but cursed without a family to share it with.

She was blessed with a beauty that seemed to be eternal, frozen in time, but cursed with a heart that would never pump blood through her veins. Rin lived on without a heartbeat.

And these curses and blessings could be traced back to before her mother was even alive. Back to before the First Hokage and even further back to when Kami rose to power.

Rin's knowledge of herself was limited to these vague pieces of information. And so she goes to the place where her lineage started, and where her curse originated.

The shrines of Konoha. There, she searches for answers on her curse, all the while undercover as the temporary Teacher's Assistant for Iruka Umino at Konoha's ninja academy.

Between keeping up selfless appearances and pulling all nighters for any kind of information on her clan's curses, Rin is steadily free falling into madness.

And it's just a matter of time before her mind decides to fall as well.