I noticed this app on Google Play recently:
This allows you to run Clannad on your Android device. Problem is, it currently only works with the original Japanese language version. You also need data from the original PC game to be transferred to your Android device. But feel free to check it out, it’s only $1.00.
Also, there’s an app that allows you to run old-school visual novels on Android. These too require you to have the original PC versions to be transferred into your Android device in order to run them.