During an investor Q&A session, Nintendo president Satoru Iwata revealed that they plan to release a Mii app to smartphones some time next year. The question and answer are currently only available in Japanese, but a NeoGAF user named StreetsAhead gave a general translation of the text. The summary states that Nintendo has an app in development for smartphones that will focus on Miis in some way. What the particular focus will be is not totally revealed, so there are a few possible ways this could go.
The quick and easy assumption would be an app that lets you create Mii characters using your smartphone. You could then possibly port them to your own 3DS and Wii U, or even take them to a friend’s house to share. However, there are other possibilities. One thing that would make the app much more valuable to players would be if it tied into the StreetPass functionality and the games available for it. Allowing users to play through, or even just manage the Mii Plaza from their smartphone would be fun and helpful. If the app actually allowed you to StreetPass in some way, such as by storing other 3DS’s information and shooting it to your 3DS when you get home. This might be a bit too much for a simple app though, but it’s worth discussing until Nintendo goes into more detail.
Apparently the app was originally planned for release this year, but the ideas continued to grow, causing Nintendo to delay to be sure they delivered a full and complete product at launch. This at least indicates that they are looking at things outside the norm, and might put in some truly nice features. Iwata was clear that the point of the app is not necessarily to do business on smartphones, but rather it was meant to strengthen the connection between Nintendo and its consumers.