@TipsyTentacle Manyuu Hiken-Cho, or as me and my friends call it, Boob-Stealing Ninjas
in an alternate history Edo Japan where social status is determined by breast size, a daughter of the ruling clan discovers a secret sword technique for transferring others' breast-size to herself (like, she slashes someone with a sword, but instead of them getting cut, their breasts get smaller and hers get bigger)