About Japan's Public Holiday Calendar
Under a provision of Japan's Public Holiday Act, a single working day squeezed between two holidays automatically becomes a holiday too; in 2026 this turns September 22 — sandwiched between Respect for the Aged Day (Sep 21) and Autumnal Equinox Day (Sep 23) — into a day off, creating a five-day "Silver Week."
Similarly, May 6, 2026 is a substitute (furikae) holiday because Constitution Memorial Day, normally May 3, falls on a Sunday that year; this substitution rule is part of what stretches Japan's famous "Golden Week" out by extra days.