What looks like some unrelatable historical piece is actually an impressive drama, about a man's life, successes, and regrets. The ending is truly great, and most shows don't come close to that elusive, satisfactory ending, or the feeling of authentic, gritty streets of japan.
It's something you won't expect to be as good as it is, but trust it a little.
I guess I need to write a bit more, i wanted this to be a short review, MAL.
Let's see, good character progression, check
Great ending, check.
There's another season after this when you come back from the past, where the main story of this season takes place, and that's good so far, in the middle of it.