"DONUT HOLE" is an original song by Hachi. He released it after almost 3 years absence in the Vocaloid community. On the surface, it is about a girl who wants to remember her past self's name, as shown in the video (Up to a person's interpretation), but can't. At the end of the song, the girl remembers the forgotten name. The lyrics are vague as to a deeper meaning and many diverse interpretations have been created.

This song entered the Hall of Myths in April 2023 and has exceeded over 50 million YouTube views. Hence, this is one of Hachi's most notable songs, and one of GUMI's most notable songs.