Part 1: Riho's fandom
Oh yeah, that image reminds me...Since this thread is apparently approaching its final days, I guess I should mention the post I did over in the weird fan art thread when I got curious and started googling her name. See, Riho's apparently pretty popular but only with a certain select group of people. You might call her the patron saint of giantess stuff because that's almost the only reason people draw her.





*dat perspective*
Then there's this poorly drawn flash animation. It involves breaking buildings, the military, and vore.


That person, for whatever reason, also hosted an entire doujin dedicated to Riho and what I assume is a good chunk of the D3 cast of characters. I put it on Imgur for easy viewing. It's untranslated though it probably shouldn't be too hard to break out my second grade level Japanese and get a rough translation out if anyone's interested. The title on the first page is "The Giant Beauty Crossover".
The last thing of note I found was some youtube video of Riho dancing and singing while giant. I'll be honest, the only reason why it's here is because I found it funny that she was knocking down buildings while dancing.
When people weren't drawing her being giant and in her swimsuit, she's in a maid outfit:



The last one's official art from a game called Dream C Club. A quick googling says it's a hostess club game for the XBOX 360 where you try to hook up with the various girls, so a dating sim but even sleazier than usual. That includes a bunch of sexual minigames but not enough to keep it off the XBOX 360. It was never translated to English, so I'm going to take a wild guess and say SelenicMartian isn't covering it next.

I mean, come on, who doesn't want to date that face?
Hope you enjoyed your dosage of weird Riho shit.