Last Christmas

Haruki Kenji is a 36-year-old manager of the Winter Sports section of a large sporting goods company. He goes on a ski trip to New Zealand with his friend Shintani Goro (who is also his boss) and Shintani's new secretary, 24-year-old Aoi Yuki. Upon returning to Japan, he finds that he has a new neighbor in the apartment next to his. It is Aoi.
While watching the movers, he sees a photograph drop from the new girl's luggage. Looking at the photo, he sees it is a picture of a group from a female bicycle gang, and upon looking closer, he sees it is a picture of Aoi. Haruki finds her putting on a facade and fooling everyone at work with her nice girl persona. But at home, she is anything but nice, dating lots of men and using them to get what she wants.
This continues until one day, Aoi comes home drunk and without her keys. Kenji lets her into her room via the door connecting their apartments. Aoi accidentally drops a video tape into Haruki's apartment. When he discovers the tape, he watches it. On it, Aoi has recorded a message to herself. Seeing this serious message, Haruki begins to view Aoi in a completely different light.