你好哈雷 (Nǐhǎo Halley)

Background
"Hello Halley" is an original song that was sung by Luo Tianyi in 2013. In 2016, a remastered version featuring Xingchen was uploaded for her character birthday and gained more popularity than the Tianyi version. Xingchen's version is featured in the album Butterfly Traveler.

In the song, Tianyi/Xingchen is a 'space mail carrier' delivering a letter to someone or something named "Halley". She expresses regret that she cannot bring them or it along with her, and becomes nostalgic about the past. Before leaving, she asks Halley to remember her the next time they meet again.