K-ON! Character Image Song Series Vol. 1: Yui Hirasawa is the first volume of the first season's "Character Image Song Series", featuring Yui Hirasawa. The album contains the songs Giita ni Kubittake, Sunday Siesta and Yui's version of Let's Go, as well as their respective instrumental versions. The songs are sung by Yui's voice actress Aki Toyosaki. The album was released on 17 June 2009 alongside Mio Akiyama's version.