"Endless Story" was written by Dawn Thomas with Japanese lyrics by ATS and was used in the film Nana (2005) in which Ito played the character Reira Serizawa.

The song samples Dawn Thomas's "If I'm Not in Love" (1993) which was also covered by Faith Hill in 1999.

At the end of 2005, "Endless Story" was named the "Best Love Song of 2005" by the Oricon magazine.

Taiwanese singer Saya Chang covered "Endless Story" and renamed it "Xiang Nian Ni De Ge".

Hong Kong singer Janice Vidal also covered the song as "Cloudy Holidays" on her 2008 Cantonese album, Serving You.