Bows, kotatsu, omiyage, the silent grammar of a polite room — the parts of Japan a guidebook can't quite explain in a list.
The genkan — that sunken step at a Japanese doorway — runs on rules no one says aloud: where shoes stop, where slippers end, and why the bathroom keeps its own pair. JP: 玄関で靴を脱ぐということ
It is not about cleanliness alone. The genkan threshold carries a spatial grammar that shapes every room beyond it. JP: 敷居を越える前に：靴を脱ぐ理由