I'm being facetious here, but I'd say, family ties. If your dad owns the company and you're likely to inherit it when he retires or dies, then I'd say there'd be a very good chance you'd be a loyal employee.
There was a time, only a couple of decades or so back, when Japanese workers were thought of as frivilous, sometimes disloyal, if they changed employers. They were tacitly promised a 'job for life.' That went out of the window when things became tough. Japanese workers were too frightened to take a holiday in case the boss laid them off. Eventually, of course, many were laid off. The employers weren't going to go under - let that be the staff. I doubt very many Japanese would consider loyalty more important than their own welfare today.
If an employer wants loyalty, they have to be prepared to make sacrifices themselves, by reducing their own pay, perks and conditions as well; set an example. if that's being done and is seen to being done, then chances are many workers will remain loyal.