For me the best anime are the ones who have philosophy lessons hidden behind the story. That's why I like this anime even though it has obvious flaws elsewhere.
If you are not aware, most stories have a message underneath, whether the writer does this consciously or not I don't know.
I believe this one tackles the meaning of life, or at least it tries to.
You have Aruka going through different stages in her life, from the emotionless robot who simply follows a code to someone who through suffering and pain grows into a balanced human being.
I say balanced here, since it pushes the acceptance of all emotions, even the bad ones. This is more or less the philosophy that the pleasure gang is about.
It goes through the acceptance of your dark side and your dark past too, as well as accepting death.
With revenge, I don't think a lot of people will have understood this but if you take revenge you are only taking away from the world, the person who you inflict revenge on is just like you, a traveler finding their own path. You can't really fix them but they may have a purpose later on in life, Aruka actually realizes her mistakes of killing people, not everyone does but they have plenty of opportunities to determine this for themselves, even if they continue their "wrong" path they still create lessons for other people.
I think the first tragic death (with the guy who was trying to get rid of towns who farmed the spirits) showed how selfish someone can be in pushing their own morality upon others, so even if you think something is wrong, you should let other people realize this for themselves so they make up their own moral code.
By taking this philosophy you're kind of letting suffering happen, in a world like this it's the strong ones who survive, and that's how evolution makes sure we stay a robust species.
TLDR: make up your own code, and let others do the same
Thanks for coming to my ted talk, have a good whatever the fuck you're doing :)
