Tail of the moon. Prequel, the other Hanzo(u) - Rinko Ueda

Set in feudal Japan, a young woman is found with a huge scar on her back and no memory of who she is. She is given the name 'Kaguya' and taken in by a local brothel where she is put in charge of babysitting and housekeeping duties. Hanzou, the head guard of the nearby castle, starts to pursue her and realizes later that they have actually met before...and are enemies! (It turns out this young woman is one of Oda Nobunaga's daughters - Princess Sara.)

In the second story, Oda Nobunaga sends Sara to infiltrate the ninja town of Iga to steal a secret gunpowder formula. She is to go under the guise of being the prospective bride of Hanzo Hattori, one of the high-ranking ninja leaders of Iga. Sara willingly goes along with the plan because she doesn't realize that she has her Hanzo(u)s mixed up!