My impression of the wearing of this particular outfit is it's a bit of slightly risqué fun that people do once in a while or as a one off. I also suspect some of the appeal is that it's so different from a lot of other outfits you usually see Kigurumis wearing.
To be honest I think it's only the 'Black & Shiny' look of the outfit that makes people think fetish (what if it were bright pink or blue?) and it's actually a lot less 'revealing' than say a two piece bikini.
I'd also like to point out that Yu looks very nice in hers - Thanks for posting the pictures





