All the pure music in the digital baby, especially about Jia Er, is that kind of sad music.
There are many songs, such as no Yukue in Nami when Whamon died, Yuugure when Jiaer was ill, and Running with the Wind played by Ahe when the children were about to leave the digital baby. (Digital Baby 1 There are only three piano songs, and I am a harmonica lover. ) These three songs are all very sad. There are many sad songs and Ben, which are the introduction of each episode. I feel very sad.