"Believe" is a song recorded by Japanese-American singer-songwriter Ai, released on April 19, 2006, by Island Records and Universal Sigma. Serving as the lead single for Ai's fifth studio album What's Goin' On Ai, "Believe" was featured in the Japanese live action drama Team Medical Dragon as its image song. Upon its release, "Believe" debuted and peaked at number two on the Oricon Singles chart. At the 2007 MTV Video Music Awards Japan, "Believe" won the Best R&B Video award.
After the release of "Story", a ballad song which later went on to become a sleeper hit in Japan, Ai released her fourth studio album Mic-a-holic Ai, which charted within the top five of the Oricon Albums chart. In early April of 2006, Ai shared to the Japanese press she wrote and recorded a song for the live action drama of Team Medical Dragon.
"Believe" is a R&B ballad in a similar vein to "Story". Produced by DJ Yutaka, Ai based the lyrics for "Believe" on treasuring other people. Barks described Ai's vocals as "soulful" and the arrangement of the song "resonates".