なんくるないさー (nankurunaisaa) is Okinawan (or Ryūkyū dialect) for “everything is going to be okay.”
なんとかなるさ is the standard Japanese equivalent.
The phrase comes from the saying “まくとぅーそーけ、なんくるないさ（ただしいことをしていれば、なんとかなるさ),” which translates to “If you stay honest, you can overcome difficulties.”
From ancient to modern times, people of the Okinawa Islands region of Japan have experienced hardships—from armed conflict to natural disasters.
The islands of Okinawa have long been prone to typhoons, earthquakes, and tsunamis.
To make matters worse, the Ryūkyū Kingdom was unable to push back the invasion of the Satsuma Clan from Japan. Since Okinawa was under the control of both Japan and China (Ming Dynasty and Qing Dynasty), the people of Okinawa were forced to pay heavy taxes for about 300 years. In addition, Okinawa is well-known as the location of the last and bloodiest battlefield of WWII, the Battle of Okinawa, which destroyed 90% of all buildings and historical landmarks and claimed 100,000 civilian lives.
Owing to these hardships, poverty was prevalent in Okinawa.
Although the initial purpose behind the phrase is unknown, the Okinawan people began to utter “なんくるないさー“ spontaneously to refocus their minds and move forward. They believe that things will take a favorable turn if they act with integrity and stay optimistic.
When the morning TV drama series ちゅらさん (chursan), featuring a girl from Okinawa, became a phenomenal hit, viewers were charmed by the beautiful sound of the phrase that her grandmother kept saying and “なんくるないさー“ became a popular phrase.
—by Ukita-sensei