The MV to Summer Wind has been uploaded to the official °C-ute Youtube channel.
Naze Hito wa Arasoun Darou? / Summer Wind / Jinsei wa STEP! will release on April 20 in six editions: three regulars and three limiteds. The regular editions come with a random trading card. The limited editions include a bonus DVD and event lottery card.
The CD covers were released earlier.
Get it from CDJapan