Tail of the Moon, Vol. 6, 6

More about the book

Usagi goes from village darling to castle clown, but that's not going to stop her from doing her best! She's going to get her man and become a ninja, and not even two super-skilled shinobi beauties can stop her! Usagi is the granddaughter of the leader of a prestigious ninja village, but she's such a klutz that she's never made it out of the kiddie class. Frustrated with Usagi's lack of progress, her grandfather sends her to marry Lord Hanzo and have lots of ninja babies. But the lord has no interest in her or her childbearing potential! Goemon and Mamezo are taken hostage by the Kanbutsu clan, and the price for their lives is an "Instant Death" poison, which Usagi must create. Their captor, however, seems intent on killing Goemon whether Usagi makes the poison or not...