What is the reaction in Japan for this?
What reaction do you expect? It's not a big deal, it would be stupid to not port the DQ series on mobile when FF is already there and selling great, and since Japan loves mobile I guess people are happy. If you are asking about the 2ch reactions I'm sure someone is already breaking their old DQ copies, like it happened when DQIX was announced for the DS, but that's not "Japan".