The Valiant Must Fall Vol. 1 (manga)

The Edo period has ended, and former samurai Haruyasu is adrift in a strange new world. Not even the promise of rebellion can cure him of his desire for death. But after an assassination gone wrong, Haruyasu finds himself at the mercy of his intended victim's bodyguard, an intriguing young woman with the power to heal--so intriguing, in fact, that he decides he wants to live in order to learn more about her.

But what will she ask in return for saving his life?