My point is just that Japanese homes are not built with any ductwork at all, aside from a vent above the stove and in the shower/bathroom. A "whole-home" device like those you linked would require installing air ducts to every room, and the homes just aren't designed for it.
Actually you wouldn't have to duct the whole house: humidity does not concentrate like heat does, but rather diffuses. So even if you only have a dehumidify one part of the house, the moisture level would level average out (over a given period of time).
Though this does depend slightly on air circulation, but a couple of tubes (e.g.) connecting floors would help balance things out.
Japanese companies produce many quality products that deal with indoor air quality:
All that said, a proper building envelope is the first thing that needs to be done. Don't know enough JP codes and construction techniques to comment on that though.
