ATLUS on the official Twitter channel shared the teaser website of the radianthistoria.jp. On the teaser website you can read the following:
In the near future
a history once told will unfold again
And an unknown path will come to be known
According to the website more information will be available on March 23, 2017 in the weekly Famitsu. Since the URL has the Radiant Historia’s name maybe it will be a 3DS / PlayStation remake or even a new game. The Radiant Historia released in 2010 in Japan and in 2011 in North America on Nintendo DS as a classic RPG game.
— アトラス公式アカウント (@Atlus_jp) March 21, 2017