Yes, スタディアプリ小学生 勉強 is completely free and it doesn't have any in-app purchases or subscriptions.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
スタディアプリ小学生 勉強 is free.
To get estimated revenue of スタディアプリ小学生 勉強 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.