Something to look out for is the part of the girl's top that's undone. If it's not made out of plastic or something it should have dropped completely. If it's in the process of dropping gravity would have pulled the lower part down at the same time (meaning it would have unfurled like a carpet with the string falling last instead of peeled off with the string leading the way, unless she wears glue or something in her top). I like that the pink haired girl's hair looks a little bit like Crona's. That made me happy cause he's one of my favorite anime characters.
Aside from that though, this is a very dramatic piece.
The strap goes across pink hair's neck, meaning she must have sat there while purple undid her top, placed her boobs on pink's shoulders, and then redid her top around them. However, pink's expression makes it seem she doesn't like what's going on. So between the fact that she's clearly made no effort to resist in quite some time, and the fact that she looks unhappy, there must be some type of coercion going on here with the adult forcing pink into this sexual situation. Unphased by the pedophilia and in fact aroused by it, this would lead one to believe that blue must have been the recipient of years of child molestation himself and now doesn't see anything wrong with it. Lastly, judging by the reaction of the cat to something that would be blocked from his view in that angle (due to the boy's leg), one can only assume that the cat has xray vision but is also mentally retarded.
That means that all four of these characters are struggling with their own demons (purple's pedophilia, pink's inability to escape a horrible experience at the hands of an adult who should be trying to protect her from such things, blue's lost innocence and warped morality by no fault of his own, and black the cat's inability to control his own super powers and rapidly degrading mental stability), and in this one moment you've managed to capture and convey those feelings. The tragedy of what should be a beautiful, relaxing day at the pool, forever tainted as these horrors collide. True, there is room for improvement artistically, most of which I feel has already been discussed in previous reviews, but the message you're sending transcends the boundaries of "pretty art". So much pain. Such a tortured soul.