[godleydemon]

well if you read the manga, basically. The one woman can cut breasts away, its a specialty of there ninja clan. Manyu, can absorb them, something that not everyone can do. So when she fights the one woman who cut away the breasts of that other woman, she steals them from her. She doesn't return them as its a constant thing through the manga, she actually doesn't yet know how to cut away breasts without absorbing them. Which eventually leads to her being so huge, she can't walk. Which is how she learns how to cut away breasts without absorbing them. Because she learns from someone who once had the ability but gave it up for a man.