...and Do As Infinity will be singing the theme song for it. Shop listings for the upcoming album release of The Best of Do As Infinity reveals that there will be an upcoming Tales of title for the Smartphone and that Do As Infinity will be the ones to sing the theme song for it.
As the name of the album implies, it will feature some of the best songs by Do As Infinity, along with two new songs, one of which will be "for a Tales of game/app for the Smartphone that will be coming out on 2014." This actually could be just an app or something, but I personally don't think they'd go all the way to have a theme song for it if it was just merely a simple app like, let's say, Tales of Bibliotheca.
Do As Infinity sang the Japanese theme song of Tales of Legendia, Tao. They had disbanded last 2005 but reformed in 2008.