I usually avoid posting images like this but I haven't been able to find a proper full scan version of this anywhere and it is too nice a work to leave nothing posted of it. Photo is from some art exhibition Ooyari Ashito did back in October 2013.
I remember checking to see if that twitter banner had been posted months ago and never found it, really don't know how I over looked it. Found out recently how to get to direct url for twitter banners this image was one I was planning to rip and post, only he had already changed his twitter banner by then.
Hopefully he'll release a full version of this image in an art book or as a poster some day.
Edit: Thinking back on it I probably just did a quick check through the artist tag back then. If I had checked Ooyari_Ashito and ballerina tags it would have shown up instantly.
The full illustration is available in 大槍葦人自選画集 LITTLE WORLD2.
Been having a fresh search for this after all this time and still not finding a full scan. I'll have to try and find a scan of Little World 2 and see if it is in that.
I need it so bad, I really love these ballet cuties.