The second moon-viewing night of autumn, on the 13th day of the 9th lunar month (October 23 in 2026). Tradition holds that viewing only Jūgoya without Jūsanya is kata-tsukimi (one-sided moon viewing), which brings bad luck. Chestnuts and edamame replace the sweet potatoes of the earlier viewing. The practice of requiring both viewings reflects the Japanese aesthetic principle of paired completion, where experiencing only half of a natural cycle creates spiritual imbalance.