The app won’t start up

Try the following.

1. Close all iOS apps that are running in the background.
2. Turn off the iPad, and then restart it.
3. Delete the app and reinstall it ... ※
   

※ Use caution, since this will erase all data and settings.

Instruction of Backup data.

1. Set your iCloud account on your iPhone / iPad.
2. Tap the Settings icon in the upper right of the screen, and tap “Backup/Restore” > “Open”. 
3. Tap “Create Backup” in the upper right of the displayed screen.