While a platform was not announced, 4Gamer.net noted that previous entries in the series have names that reference the console names themselves. For example, Radirgy PreciouS was released for PlayStation 2, and Radirgy GeneriC was released for GameCube. That being said, it is possible Radirgy S will turn out to be a Switch title.
Here are some screenshots from the announcement:
Thanks, Games Talk.