A strange, low-key, and fairly low budget Japanese film that's kind of in the tradition of "Man Facing Southeast" (or its American knock-off, "K-PAX"). That is, it's about aliens coming to Earth - but they're not identifiable because they look entirely human. (Which also conveniently means your filming budget is lower.) In this case, three aliens have landed as the vanguard of an alien invasion: it's their job to get a better understanding of humanity. The three take over the bodies of regular people, and then proceed to develop their understanding by taking concepts from people - unfortunately, when they take a concept (such as "work" or "property"), it's entirely removed from the person they took it from. So they leave a trail of people with significant mental problems behind them. These aliens are generally quite willing to explain what they're doing, but for the most part people don't believe them because they look entirely human (although they don't always act it).
If you're thinking this sounds weird, it absolutely is. But the script and acting are very good: I found the movie really fascinating and enjoyed it immensely. Fans of science fiction who mostly like explosions won't be into this (there are a couple at the end, but that's really not what it's about), but fans of thought-provoking SF should try to track this one down right away.