This is a story about love and return. The person who is always by your side is often ignored, as if she is as small as dust, as if she should be here. Until she left, the feeling of loss told him that it was completely opposite to what he had always believed. There is only one bird in the world that can fly backwards, and that is the hummingbird. How heavy is the human soul in this world? It is said that when a divorced wife leaves, the remaining withered body weighs exactly 21 grams less than when she was alive, which is exactly the weight of a hummingbird. So can love that is in communion with the soul fly backwards like a hummingbird?