The 180-Day Rule (jutaku-shukuhaku-jigyo-ho cap)

This is the single number that reshapes every Japanese short-term-rental pro forma. The 180 is guest-nights actually occupied, not nights you are allowed to list, and it resets every January 1 with no rollover of unused capacity. Municipalities can tighten it far below the national maximum: Kyoto restricts most residential zones to roughly 60 days a year, and several Tokyo wards add their own overlays. After cleaning turnovers, gap days, and local rules, a realistic practical ceiling is often 130-150 nights. Exceeding the cap counts as unlicensed lodging under the hotel/ryokan law, and OTA platforms increasingly enforce day counts automatically. If you need to run year-round, the only legitimate escapes are special-zone minpaku or a hotel/ryokan license.