Yes the boobs look natural but...
they look unhuman large in comparison to the bodies of these animegirls.
In my Opinion these proportions arent possible in reality without doctors help:
aku no onna kanbu full moon
immorality
baku chichi bomb
Sadly most of the hentais have a japanese/fantasy attitude or other stuff that doesnt fit for me: Shemales, tentacles, different skin colors, dont ask for the story.....
If I could draw like this i would create my own hentai anime/hentai...