youth case is a music unit of two Japanese songwriters and producers. According to the official website of KIMONO Inc., Tokyo Japan, they are childhood friends and have started their career together in the music industry since 2005.
“youth case” is credited as a lyricist for「Kissからはじめよう (Kiss Kara Hajimeyou)」by 嵐 (ARASHI), a side-B track of their 17th single「アオゾラペダル (Aozorapedal)」, released on August 2, 2006. This is the very first of many songs they’ve written for Arashi.