If you don't know yet, there is a sister movie called "To Me, The One Who Loved You" which released on the same day as this one in Japan. I will watch that one next and edit this review after that.
Why? Because, as a standalone movie, I didn't get much from this one alone. It was thought-provoking, and touching at times, but above all else: confusing and leading nowhere. It really felt like I was watching a sequel or spin off, because there was just SOME information missing to make what was happening on the screen (especially after the first half) make any sense.
My guess is that you have to watch both movies back-to-back. I will update you guys after I have done so :) As off now: not recommended to anyone except people who enjoy a philosophical essay about future technological advancement. Because that was all the movie could be for me.
