This movie is not as devastating as Takahata's Grave of the Fireflies, but still somewhere around there on the top 10 most miserable movies (at least for me).
I had this experience before with some movies, when more or less all is lost, what is even left to live for? That's obviously a very dark question to ask, but for a movie like this, I just ended up losing hope towards the middle, even if a lot happened the second half.
The last 10-15 minutes really hit me hard and I wish there could have been more slow, thoughtful moments like that.