A single for two weeks in a row! Includes four tracks in total. This edition comes with a bonus DVD featuring a music video of the title song and its making-of. Also includes a 24-page lyrics booklet and a trading card randomly selected from ten kinds. Tall digipak packaging.

TRACKS
DISC 1
01. HAPPY HAPPY (日本コカ・コーラ Qoo CMソング)
02. The Best Thing I Ever Did -Japanese ver.-
03. HAPPY HAPPY (collapsedone Remix)
04. HAPPY HAPPY (Instrumental)

DISC 2 [DVD]
01. HAPPY HAPPY (Music Video)
02. HAPPY HAPPY (Music Video Making Movie)