A Blue Automobile (2004)

A ubiquitous pair of sunglasses helps d.j. Richio (Arata) hide behind a super-cool facade while also concealing a disfiguring facial scar. He's haunted by nightmares of a childhood accident whose physical remnant is nothing compared with the psychological wounds he silently stores up, despite an apparently healthy rapport with vibrant g.f. Akemi (Kumiko Aso) and decent employment at a record shop.
Akemi's schoolgirl sister Konomi (Aoi Miyazaki), attracted to the punkish Richio, shows signs of interest, which he picks up on. Notwithstanding the sisters' tight relationship, Konomi and Richio have sex, deeply wounding Akemi when a remorseful Richio confesses to the liaison.