I guess it depends on where you live. I've been in Japan about 20+ years... in the "countryside" I never saw them being built, but here in Shizuoka you see them

I guess it depends on where you live. I've been in Japan about 20+ years... in the "countryside" I never saw them being built, but here in Shizuoka you see them a lot. Personally, I'd never waste my money on them... the one's I've seen use really cheap materials for walls and doors. I could probably fall THROUGH a door if I tripped...