It's from Higurashi no Naku Koro ni Chikai (the second live action movie). It's one of the sides on the reversible DVD jacket that comes with the Collector's Edition.
keonas said: Why are they suddenly wearing skirts instead of buruma? And what happened to Mio, she looks 3-4 years younger than usual?
Because in Chikai, that's how their uniforms look. If you look at the image for the first movie, their casual clothes are the same as their movie counterparts as well.
As for Mion... that's probably just the artist's doing/mistake?
