From May 10, 2026 to May 14, 2026, the corresponding solar term in the Nijūshi Sekki (24 solar terms) is 立夏(Rikka), and the corresponding microseason in the Shichijūni Kō (72 microseasons) is 蚯蚓出(Mimizu izuru).

What Is “Mimizu izuru” (蚯蚓出)?

"Mimizu Izuru" (蚯蚓出), meaning "the earthworms come out," is one of the Shichijūni Kō (72 microseasons) — Japan's finely grained way of capturing the subtle shifts of the year. It falls as the second microseason within "Rikka" (立夏, "the start of summer") in the Nijūshi Sekki (24 solar terms), corresponding roughly to May 10–14. The name says it simply: this is the time when earthworms, having been at work beneath the soil, begin to appear on the surface — a quiet sign that summer is steadily drawing near. The Shichijūni Kō is a traditional Japanese calendar that marks the changing seasons in intervals of roughly five days, born from a culture attuned to the smallest movements in the natural world. What makes "Mimizu Izuru" so distinctive is that it finds meaning not in any dramatic shift of scenery, but in the unhurried stirring of life underground. People of earlier times read in the earthworm's activity a deeper message: the soil was warming, and the season for things to grow had arrived. In the busyness of modern life, it is easy to let the turning of the seasons slip by unnoticed. But knowing a word like "Mimizu Izuru" invites us to look a little closer — down at the ground beneath our feet, where, quietly and without fanfare, the world is always changing.

List of Japan’s 72 Microseasons