The only Japanese drama was from the early 1990's. The main story was about a girl who lived with her father; I believe she was being sexually abused by him. A side story was another girl who took a liking to her teacher at school. I'm sure I've just described about a score of Japanese dramas from the early 1990's. I really liked the song.
Anyways, in the end, I think the main girl's friend (who, if memory serves was also a teacher) kills the father and they both flee. The story ends with the 2 of them on a train trying to escape. The last scenes are the cops arriving at the train station to apprehend them and the 2 of them are asleep (dead?) on the train.