Kaoru and Sentaro’s medley from episode 7, using the same clip, but with the voices muted from the anime. Nothing but glorious jazz music~
The song is called “Kaoru & Sentaro Duo in BUNKASAI” from the OST, and is a medley comprising of 3 songs also featured in the anime. These are “My Favorite Things”, “Someday My Prince Will Come”, and “Moanin'”, arranged by the amazing Yoko Kanno.
Again, I do NOT own Sakamichi no Apollon or this amazing music.
Here’s the original scene: http://q.gs/4c13K
WACOCA: People, Life, Style.