A Korean number from "High School Musical on Stage!"(2007), which is based on film "High School Musical"(2006). The musical performance was in 2013, the soundtrack of this version wasn't published. This is for promotion.

Links:
[Ryeowook(SUPER JUNIOR), Luna(f(x)) - 우리의 시작을 (Start of Us (Start of Something New)) (   • Ryeowook & Luna (려욱 & 루나) - 우리의 시작을 (...  )]
[Studio recording/promotion video (   • [하이스쿨뮤지컬 High School Musical] 려욱, 루나 ...  )]