 Sora, Riku, and Kairi are named after the three primary elements of  nature. In Japanese, riku means land, kai means ocean, and sora  means sky. the name Kairi could originate from the Japanese word  "hikari", which means light, because she is the only untainted main  character. "Hikari" is the Japanese version of "Simple and Clean,"  though the lyrics have an entirely different meaning.