Final thoughts, after watching all 4 hours: It's a Terminator story. Lots of chase scenes, some gruesome deaths (probably more than any live-action Terminator), and lots of discussion about what it means to travel through time, and the nature of free will and fate.
And all of that mixed in with a story about young kids trying to connect with their father after their mother's death. And a father that is *choosing to neglect his kids*, in order to try to save them from a truly terrible future he dreams about every night.
There are some fun bits relating to it being set in Tokyo - "I need guns, where can I get some?"..."this is Japan, nobody has guns!", that sort of thing.
Overall, I quite liked it. Didn't quite stick the landing, emotionally, but well worth watching if you like this sort of thing.