These sketches are great, and this one's definitely my favorite. By the way, is Ruri doing a parody of something? If I had to guess, I'd say it's something from touhou, but I'm not familiar enough to tell.

Don't forget she's a fan of an in-series anime series (Maschera or what-not). Could be from that *shrug* But Touhou is possible since the artist as an affinity for that franchise as well.

I've been in a sketch style binge with Pixiv lately. My last batch of uploads (I don't upload much) were mostly skteches as well ^_^