In Kuronosuke Shirata’s Chichi no Jikan (“Breast Milk Time”/“Father Time”), a young biology student comes face to face with some aliens who decide to come to his home.
They come bearing a baby and a demand: He must raise the baby for an entire year, or the world will be destroyed.
He turns into a woman with very large breasts meant to do this job well, which is understandably confusing.