Woah... OK I am not a fan of Ai Uehara either (managed to miss each of her 50 retirement vids) but how is she not "girl-next-door" stereotype. The Urban dictionary version is IMHO invalid here. That version is about the girl that one (young guy) may have the hots for. First of all, that's a IRL situation. Here we are discussing JAV. Second we are talking about generality (within JAV) and/or typecasting. E.g. Ayumi Shinoda is a typecast MILF. Shuri Atomi 跡美しゅり is a slutty lolita typecast, Aika is a black gyaru typecast, Hitomi is a milk bags typecast.
Aika is a particular interesting example, I happen to think she's a terrible gyaru, she s' not at all convincing trying to carry the bitchy "I"ve run of out fucks to give" (yea is there a pun in there?) persona. But she wear that spray-tan 365 days a year so we have to give her that typecast.
For girl-next-door, the moment she starts undressing or even kissing a guy, even the moment she start having a real conversation (not just greetings) we have to stop judging her girl-next-door-ness. How she's a hyperslut once she's in the bedroom (or dungeon!) is totally irrelevant.
I think a girl-next-door typecast in JAV can have an objective definition: a girl or young woman who's cute or pretty but not amazingly beautiful (therefore intimidating) whose make-up, dressing habit, mannerism isn't particularly sexy, gorgeous, glamorous, or even very self-conscious. Attractive and desirable but not conspicuously so.
Ai Uehara, while still clothed, in the typical cloths that she wears for DVD covers etc, is perfectly representative of 'girl-next-door'. Particularly, her tits aren't small at all, but how she dresses typically doesn't make you focus on her figure. Samewise her face is pretty but not traffic-stopping beautiful is hallmark 'girl-next-door'. The fact that we have all seen her done the most depraved sex acts with any men or things that moves or probe or squirt slimy fluid is quite besides the point. Her biggest selling point is she's the girl next door who's really a nymphomaniac.
Yes... I understand... last few months she's trying mighty hard to establish some kind of sucking/fucking/sodomizing world record with her retirement videos and so our perception has been distorted but objectively speaking, (ok... let's exclude her most recent catalog) she's still the girl-next-door typecast up to (almost) the end.