Lol. Stephanie... She's not too bad looking for a White girl, honestly, though (yeah, that was pretty racist, but sorry, that's just how I feel >_>).
I think that the ugliest girls in J-Pop, hands down, are misono, Kana Nishino, and Miliyah Kato. Funny, though, Miliyah actually DOES look good sometimes (she looks okay on her new album cover, for example), and some very rare times, even, she can appear like quite the exotic beauty. But for the most part, I think that she looks pretty gross (but I could see somebody disagreeing with me). I think it's because she doesn't look too good with a lot of make-up, and they often really do her up. Plus, they give her ugly ass hair and outfits a lot. -_- Kana Nishino is just......yeah (some may think she's..."cute", I suppose, but it has to only be in the way that ugly dogs are cute, lol, or because they try so hard to give her that image that it manages to rub off on people). And her fishlips make it that much worse. misono......do I really have to say anything? (There can't be one normal person in the world who doesn't find that girl repulsive, there just can't. Sorry for being so blunt, but I've yet to hear anybody disagree in the slightest. )
Kumi Koda is a very close contender for ugliest J-Pop girl, in my opinion. She's only saved because, despite the fact that she naturally looks like a fifty year old drag queen who didn't take care of himself, she's usually gorgeous with make-up and Photoshop (and no, not everybody can look that good, or that different, with professional help, hah). But yeah. If you go by how somebody looks with light or no make-up...... Fucking ew. She may take the top. Namie Amuro is another one that has so fucking much Photoshop and make-up all the time, so she usually looks okay, but even in normal lives, she usually looks significantly less beautiful, and if you've ever seen the girl without stage makeup....whoa. D: For me, it's mostly about the massive forehead and elongated neck, lol.
Two women that I generally think are very pretty, yet have had horrible periods of butt-ugly-ness are Mika Nakashima and Ayumi Hamasaki. For Mika, she's another one that looks bad with a lot of make-up. She's best in more natural states. And Ayu, it's not that she can't wear a lot of or too little make-up, but rather, there are certain styles that age her, and others that simply make her look really bad. Same for hair. Honestly, I know that she loves short cuts, but they rarely do her any good. There was a picture of her from not too long back, with her most recent cut, that really made me think of a Korean boyband member. :X
Oh, and one more. lecca. I still can't decide whether or not I think she's strikingly attractive or just weird looking, hah. I think that I'm confused because of her shark teeth......'cause everything else is okay.
As for men, pretty much all guys from boybands are fairly ugly, in my opinion. They're all so plain at best, and you can tell that they'd mostly be very unattractive without the professional help.
(I didn't provide any pictures, considering I'm highly certain that everybody here has seen at least a few pictures of who I'm talking about. If anybody wants me to show them the ugliest pictures I've seen of these people, if you don't agree with me, I'm sure that I could do that, hah.)