ImDown is the name of this app.

If your parents' smartphone had not used for a while, it sends you an SMS.

Use it for health confirming of your parents living far away, etc.

If your parents don't use smartphone very much, make a charging stand on the refrigerator door. It's effective.

※For smartphones with battery saving mode,
　Auto-startup and background services may not work correctly.
　In that case, Please allow it yourself from the individual app settings on the system settings menu.