K-On! An unexpectedly beautiful moment

This is a brief clip from Season 1, Episode 4 (Training Camp!).  Mio the bassist has been frustrated by the rest of the band's seeming lack of enthusiasm for practice.  Then her bandmates put on this show for her.  There is so much left unsaid in this scene - very little explanation other than a reference to the club's "Budokan or Bust!" goal.  The viewers hear next to nothing of Yui's actual guitar playing here - instead we hear a soft, instrumental ballad kick in, perhaps reflecting Mio's emotional reaction.

There's just something about how the animation, the joy on Yui's face, Mio's reaction, and the music all come together for a few seconds of extraordinary beauty: