"Spirit Cage". The song title of the BGM of "Ling Cong Hong Kou" is the same as the animation, so it is "Ling Cong". Background music is also called accompanying music or soundtrack; it usually refers to a kind of music used to adjust the atmosphere in TV series, movies, animations, electronic games, and websites. It is inserted into dialogues to enhance the expression of emotions and achieve a kind of atmosphere that attracts the audience. An immersive experience.