Twitter user @regularpanties, who discovered and extracted the file, did so by data-mining a decrypted version of the PS Vita demo.
The file for the song is titled “2mix_refantasy_キャサリン用_180404,” which translates to “2mix_refantasy_forCatherine_180404.” You can listen to the full eight-minute track here.
While the song does not play in the demo itself, it is categorized as one of the tracks playable on the in-game jukebox.
Atlus previously teased the Project Re Fantasy concept video music in Catherine: Full Body via the game’s opening movie, which featured a shot of the jukebox.
As pictured above, there are two tracks for Project Re Fantasy, titled “Concept Video 1 BGM” and “Concept Video 2 BGM.” There is also a space beneath those two tracks that is empty—and it is the only empty space on the jukebox. It is possible that more music from Project Re Fantasy will fill this space, given that the jukebox is organized by title.
In recent interviews with publications such as 4Gamer.net and Famitsu, Atlus Studio Zero creative producer and game director Katsura Hashino teased a potential official announcement for Project Re Fantasy in 2019. In the past, Hashino has also said that the studio would gradually share more information on Project Re Fantasy after the release of Catherine: Full Body on February 14 in Japan.