Japan Postal Lookup

Choose this endpoint when you need to resolve a Japanese postal code to its address components, or find postal codes matching specific geographic components (prefecture, city, ward, town), using an authoritative Japan Post local data snapshot. Prefer it over general geocoding endpoints when the primary key is a postal code or address subdivision rather than a free-text address string. Use Japan Address Normalize or Japan Address Parse siblings when the input is a free-text address string rather than structured components.

• Invalid postal code format (must match \d{3}-?\d{4}) returns validation error
• No matching records found for given postal code or address components returns empty candidate list
• Ambiguous or incomplete address components may return too many or too few candidates
• max_results out of range (below 1 or above 50) returns validation error
• All fields null/missing with no search criteria returns error or empty result