Aruka the evil spirit who devoured a human and her "human" side thinks she became a god?
Yep, I think this option, will very sad, my reasons:
1) She doesnt miracles
2) Only we see spirits, there isnt land gods
3) she has and doesnt have a physical body, by ex. she can touch her food, but not a living creature
4) in this work ghost eat human feeling, but in other works, ghosts ate smaller ghosts)
5) dead people become??? Ghosts? Or to the heaven?
My theory is, she was a human with a big ghost parasyte, it was eating her soul and she become between living and ghost, now they are in balance, She loss a lot of living creature feature but she can interact by the moment and stay with a human form and not degenerate at a ghost monster, she is like a Scylla monster