"Heart" is Do As Infinity's second single, and the first of four singles with remixes, released in 1999.
This song was included in the band's compilation albums Do the Best and Do the A-side.
- "Sariyuku Yūbe" (散りゆく夕辺 Dying Night)
- "Heart" (Instrumental)
- "Sariyuku Yūbe" (Instrumental) (散りゆく夕辺 Dying Night)
- "Heart" (Keith Litman's Heart Head Remix)
- "Tangerine Dream" (RAZOR N'GUIDO Remix)
- "Tangerine Dream" (Dub's keep on Remix)