Today I was in Shiodome and stumbled on the National Center (National as in National−Panasonic). National makes all kinds of household items from refrigerators and microwaves to Japanese style bathrooms, kitchens, and living rooms. In Shiodome they have a large showroom where you can see all their different interior offerings.
One floor had fairly fancy high class rooms showing off different interior designs. Some of them were very cool but the one that really stuck out was this one...
You might be able to see a few more pictures here.
The description for the room was as follows
Translated that basically means "Enjoy a house with a moderately separated couple feeling". That's actually kind of hard to translate directly but if you look at the diagram above hopefully you can see that there are separate bedrooms on each side of the bathroom. In the bottom one you can see that it has it's own entertainment center so in other words you can live on opposite sides of the house and have your own life, no need to be bothered by your spouse.
I gotta say, my stupid American point of view finds that really sad and yet the kind of couple that would consider that kind of arrangement in Japan is not uncommon at all. There is more stigma to divorce here in Japan than in America so rather than get a divorce and try to find someone new to share your life with many Japanese just 我慢 (endure it) and do the best they can short of actually getting a divorce.
I actually stayed with one a few years ago. I was visiting a friend of a friend and her parents lived in a house where the father and mother each had separate rooms about 25x20 feet large. (This was not in Tokyo). The rooms being that big, each basically had a bed and a living room to themselves. They shared the kitchen and dinning room. I have no idea how much they actually interacted with each other.
I can't personally imagine being in that arrangement. My sensibilities say fix the relationship or get out. If we no longer want to be each other's best friend then separate. But, maybe this arrangement works for others...