This is a fairly common misunderstanding of these types of illustrations. These are not children, just child-like characters. Think of Wikipe-tan, for example. So these are sexualized versions of child-like characters, which is technically not kiddie porn even if some people find it disturbing. Sometimes when Wikipe-tan is shown in a sexual context, her proportions are made more adult-like, as in File:Wikipetan-minna-calm.png, which is part of a series of Wikipe-tan for the same strip poker game as the image under discussion. So the child character Wikipe-tan can be shown dressed up in the maid outfit, but they are at the same time an adult, so there's nothing wrong with seeing them strip and masturbate. You see?
— A Wikimedia Commons user
