Tomoya and Naomi Sato, looking to buy a home in one of the world’s most expensive cities, bought a tiny plot of land in a crowded residential neighborhood in central Tokyo. The land was steps from a street lined with mom-and-pop shops and across from an elementary school.

The couple hired an architect known for building small city homes with bold designs: 38-year-old Osamu Nishida of ON Design Partners. Still, when they received a building plan, they were flabbergasted.

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