Wikipedia refers to this as a "Japanese romantic drama anthology film." It consists of three individual stories, "Magic (or Something Less Assuring)," "Door Wide Open," and "Once Again."
Each of the episodes is about relationships. The first sees two best friends talking about one's enchanting evening with a new guy ... but after the talk is over, the other woman goes to see a guy. Who turns out to be her ex-. What ensues is ... not pretty. She struggles to do the right thing but isn't terribly good at it.
The second episode sees us visiting a friends-with-benefits relationship between a young male student and a slightly older (but still young) mother who has returned to college. The man hates a professor for setting him back a year, and uses sex to blackmail his benefits partner into blackmailing the professor. This doesn't go well, as one might expect. This episode also includes ten minutes of the woman reading out an oral sex scene from the professor's book, to the professor.
The final episode is two high school friends meeting by accident for the first time in 20 years. But there are strange revelations hiding around the corners of their nascent relationship, and neither of them is all that happy in their current lives.
None of these stories consist of social situations that make any damn sense or even seem possible to my North American mind. I need to clarify that: all the situations seem possible, it's how they play out that didn't feel real to me. So the movie was at best "interesting," but I can't rate it as "good."