by2's song "Once Upon a Promise" is good. As for "Flying Feather", it is not actually by2's song, but sung by Li Dongyan and Cui Yan.

Information: There are different opinions on the Internet about who the singer of Feiyu is. Some people say it's Dong Zhen, some people say it's Cui Yan, and some people say it's BY2, but after multiple verifications, there are two versions of this song: one is the official release version of Cui Yan and Li Dongyan, and the other is Cui Yanhe Dong Zhen's early trial version was not adopted because Dong Zhen's voice was too soft. "Feiyu" is tailor-made for "Fantasy Zhu Xian" by the industry's top music production team. This song breaks the solid pattern of the three ancient and three new Chinese styles (ancient poetry, ancient culture, ancient melody, new singing method, new arrangement, and new concept). In the lyrics part, it incorporates the background of the story of "Dream Zhu Xian" and adopts a more traditional style. The lyrics are written with a gentle artistic conception, giving "Fei Yu" a beautiful love story; in the composition part, "Fei Yu" fully combines the rich fairy style of "Dream Zhu Xian", with three sighs in one song and a long meaning. , and highlights the joyful freedom of unlimited flying using the flying immortal system in "Fantasy Zhu Xian". Flying to the Beauty that Belongs to Us Regardless of the wind and rain, "Flying Feather" is the first test opening song of "Fantasy Zhu Xian", showing us the unique fairy style of "Fantasy Zhu Xian". The whole song is performed with various musical instruments such as guzheng, ancient flute, and ancient Xiao. The ethereal female voices vividly interpret the determination of love to pursue dreams. They use their voices to depict for everyone a picture of elegant people holding hands with swords. Picturesque scenery at the end of the world.