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 (Lip Sync ver.) and cover photo shooting footage. Also includes 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 Lip Sync ver.)
02. Jacket Shooting Making Movie