Here are some charts on the Vita's progress so far in Japan.
http://www.thesixthaxis.com/2012/02/08/ps-vita-sales-market-share-and-the-3ds/
Read my original story on Fictionpress (Shinigami Twin): http://www.fictionpress.com/s/2996503/1/Shinigami-Twin
As well as my other one (Hell's Punishment): http://www.fictionpress.com/s/3085054/1/Hell-s-Punishment
Nintendo Network ID: kingofe3