The evil of demons and ghosts stems from the malice of the human world. Human kindness can also dispel even the deepest resentment. True evil lies not in demons and ghosts, but in the greed and malice deep within people's hearts.
The protagonist starts out wanting only to live a comfortable, ordinary life, but eventually takes on the responsibility of protecting the human world. The story explores the eternal question of "the greater your power, the greater your responsibility" and the preciousness of an ordinary life.
