It’s not really a spoiler to point out that Steins; Gate involves a boy who dresses as a girl.
The latissimus muscles seem to be manly. Other than that, I have seldom seen a man with such a feminine aspect.
When a male and female model are put together, it becomes easier to call up points of contrast.
When an actual adult woman is depicted, it is interesting to note the relative unimportance of details like skin smoothness, lip color and hair length. The shape of female musculature is simply different. In the case of Bouguereau, the 2-D view is so evocative that one could make a 3-D sculpture based on just one perspective.