Breast expansion is a trope tag for scenes in which a character's breasts visibly grow or swell larger over the course of the story, usually triggered by magic, a curse, a potion, or some other transformation device rather than natural growth. It's a popular subset of the broader transformation category, prized for the gradual visual change itself. Breast expansion hentai doujinshi and manga built around this growth trope can be found on Top Hentai.
