Sayu is not 18 yet and I thought the legal age in Japan is 18 for most part except in drinking (and maybe smoking I think)?
Age of consent nationwide in Japan is 13, some prefectures put it at 15, and usually is accepted that once a model or idol is 16 the pics can be a lot racier than before (without full nudity), that's why you see Junior Idol sites making the distinction between U-15 (under 15) and U-18 (under 18 ). And Himalia is right, this PB is aimed at a japanese audience, and the perception is different there.
And yes, according to my country's laws she's been legal for a year, but I expect her PB to be about her cuteness, and if some "more adult" shots are in it, then that's a bonus
