It's that little button on the top right. It's the same as the search tab. You have to update to the latest firmware first to get it. Also, you can now scan QRs from eShop from the settings tab now.
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