Kaiware Daikon Sprout Day (Kaiware Daikon no Hi)

Established in 1986 by the Japan Kaiware (Daikon Sprout) Association. The date comes from a visual wordplay: if you turn the number "8" on its side, it becomes the infinity symbol "∞," and writing a "1" beneath it makes the whole shape resemble a daikon radish sprout (kaiware daikon) — hence the 18th.