I think the perviness of this PB is highly over-rated. The bikini shots are by no means pervy. Can you honestly tell me that the following shots are pervy?
She's got a great slim well-toned body. Better than Koharu, who, for a growing young girl, is just too skinny, IMHO. But Risako obviously got no... "feminine assets" to show off. That last shot, with her back arched back is a textbook shot to show of a woman's ass, and it's clear she doesn't have one. The art director showed restraint in choosing her bikinis - they are all very low cut and have that frilly stuff that little girls like to have on their bikinis (and let's face it, even little girls wear bikinis these days). Besides, a full cut navy-blue school swim-team 1-piece swimsuit would be much pervier, given the extent that they are used in fetish porn these days.
The only borderline shot I could imagine would be the following:

And even then, it's all in your imagination. The perviness in all in your head,
If somebody is turned on by cuteness, then there's really nothing that can be done, because there's nothing wrong with cuteness alone. That being said, these following two photos are awe-inspiringly cute, some of the best I've ever seen of her or any other H!P girl.

Give her a year or two -
then she'll have some hips and we can all start worrying about whether she's been pushed too much too fast.