First, try closing the app completely. Then reopen it and check if there's a reset button or option in the app's menu. Sometimes, you might also need to uninstall and reinstall the app to reset it.
Resetting the 'High School Story' app might vary depending on the platform you're using. On iOS, you could go to Settings > General > iPhone Storage, find the app, and select 'Offload App' or 'Delete App'. For Android, it could be in the app settings or through the device's app management settings.