Remorse, Regret
The only feeling a dead soul will have is remorse. Remorse for the people it left behind. Regrets for the things it did and didn't do.
If you died right now and left your soul behind, do you think you'd have regrets?
かん
うら
None
The soul with the most regrets is Genghis Khan (かん). Everyone knows to stay away from him in the spirit world because he's so sad. Not because of his own actions, but because of the state of his people now.
Picture Genghis Khan looking down at the state of his people, the Mongols, in the modern world. See the remorse in his soul's face. They should be leaders of the modern world. Not reduced to a people struggling in the background.