kō

 A microseason in the traditional Japanese calendar — a period of approximately five days named for a specific natural event occurring at that time. There are 72 kō in a year, three for each of the 24 sekki. Examples: "The east wind melts the ice" (February 4–8), "Peach blossoms begin to bloom" (March 10–14), "First rainbow appears" (April 15–19), "Harvest moon" (September 17–21). Each kō is a five-day act of noticing.