I dont think high skilled young workers, will be looking forward to taking care of the large number of old people, when Japan hits its population cliff. That probably will be a big sector demanding immigration.
Old people could probably take care of even older people, will easily create lots of jobs.
That being said though, a number of potential applicants would probably be discouraged by the 10-14 hour work shift. I'm not sure how much of that is spent working, but that doesn't as much room for leisure, regardless.