The presentation is flawless: the fantastic cast & the direction, great choice of music and the jaw-dropping cinematography. One thing that stings me a bit is that the plot maybe goes a bit too far. It's like the developments of the plot are being smacked on the wall with neon colors; risking it to become in parts nearly ridiculous. But still ... being so extreme (and quite surreal) serves the in bold letters written message quite well: Be nice to people, they are a very fragile bunch.
Great film! For me a masterpiece as well. I highly recommend it!
Additional thoughts: From the recent two decades there are many dark Japanese films and animes, which focus on egomania and psychopathy in context with society. Many of them fairly mainstream ones. It seems many people started to feel the downsides of a tightly organized and packed society only after the economy crashed in the 90's. Stress, anxiety and especially the inevitable need to keep silent helped brewing a state of panic and purposelessness in them.
The reason why all these novels, mangas, art exhibits, animes and films etc pop up is probably simply nature. Trying to reverse certain developments, pointing out large areas of society which needs healing. One thing "Confessions" certainly underlines is the need for reliable moral guidance when human beings are small, vulnerable and quite irritable. In a nutshell: the need for love.