(warning: possibly stupid question ahead)so, if any, which bonus would come from preordering the game on Play-Asia?
What BT said. Play-Asia usually only packages the official bonuses from the publisher/developer for preorder.From the official page, the best guess is the magazine and the trading card.
quoted this from play-asia's description of im@s ds>Fear not, for you are not alone. Established idols such as Amane Haruka will show up to guide you along. Listen to their advice and see how your meeting with them will change your path.