「COLORS – Hikaru Utada」Wiki
"Hikari" (Japanese: 光?, "light") is Hikaru Utada's 10th Japanese-language single (12th overall), and is also her 3rd single on the Deep River album. Its release date was March 20, 2002. It is best known as the main theme song for the Japanese release of the Square (now Square Enix) and Disney Interactive Studios video games Kingdom Hearts, Kingdom Hearts: Chain of Memories, Kingdom Hearts Birth by Sleep, and Kingdom Hearts Re:coded. Utada was the only singer that Tetsuya Nomura, the director of Kingdom Hearts, had in mind for the Kingdom Hearts theme song. This also marked the first time Utada had produced a song for a video game.
(Wikipedia contributors. "Hikari (song)." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 11 Apr. 2014. Web. 4 May. 2014.)