|The 12 Japanese zones
|Principle of North American zoning: exclusive use per zone
|Principle of Japanese zoning: zones include all uses up to a maximum "nuisance level"
|Allowed uses in every Japanese zone
|Single-family houses and low-rise apartments coexisting in Sendai
|Same area, as seen from the sky, in green, single-family homes, in red, multifamily apartments
|Height restrictions in Japanese zoning to avoid eternal shadows
Note that this guideline also exists in North American cities, but is often bypassed by arbitrary height limits written in every zone..
UPDATE: For an example of the great mix of housing that results from the lack of regulation on housing types, see this article on the housing mix of a small neighborhood in Sendai.