Today, July 16th, is 「Rainbow Day」!!

July 16 is "Rainbow Day." It is derived from the pun "nana (7) i (1) ro (6)" and the fact that large rainbows tend to appear in the sky around the end of the rainy season. It was established by designer Yasuhiro Yamauchi. In addition, July 16 includes the following commemorative days and historical events:
Ekiben Day: Commemorates the first Japanese ekiben (station lunch box) sold at Utsunomiya Station in 1885 (Meiji 18) (a set of two rice balls and pickled radish for 5 sen).
Mustard Day: Commemorates the establishment of the predecessor of the Japan Mustard Cooperative Association on this day in 1957.
Enma-sai Day: Along with January 16, it is considered a day when the lid of hell's cauldron opens and both demons and the dead rest, with visits to Enma halls at temples.
Ministry of Land, Infrastructure, Transport and Tourism Day: A day to understand the significance of land, infrastructure, transport, and tourism administration, commemorating the establishment of the ministry.
As a historical event, July 16 is also the day in 1945 when the United States successfully conducted the world's first atomic bomb test (Trinity Test). (Source: Google)