Sony is pushing out the Android 4.4 KitKat update for the Xperia Z Ultra smartphone. Users in Hong Kong are reportedly getting the update first. THe update is only available as an Over-The-Air update so owners would not be flash it manually.
However, it is worth checking the settings for an update as it should be available there. It is a phased roll out and the update may not be available if you live in North America.