yes but doubt many of them look like under 16.
I know a woman with four kids that barely looks older than Yuki - she's in her mid 30s. Same body style, same A-cups - she might actually be smaller than the size Yuki is portrayed.
What does 18 or 19 have to look like? Does she need to have wrinkles already?
Some folks here are majorly reality challenged. In actual reality, 18 year olds that look 18 do exist. The girls I knew my first year in college looked just the same as the girls I knew from about my sophmore year in HS and beyond. At that age, not nearly as much changes. It isn't until about the mid-20s that most women start to lose a bit of that "youthful" appearance, at least in my experience with the many thousands of women I've known and met over the decades. I also know many more women that are naturally A or B than I do beyond D - the volley ball and beyond sized breasts that so many people here associate with "now THAT'S a woman" are the exception, not the norm. Many of the women you see IRL with breasts that large only have breasts that large due to modern science and surgery.