Named “2mix_refantasy_キャサリン用_180404” within the game files—or “2mix_refantasy_forCatherine_180404″—this song was featured in the first and second concept videos for the game, released respectively in December 2016 and December 2017.
The time stamp for the song in the files is of April 4, 2018, via @OtherEhm.
This song was first indicated in a list of songs available in the Catherine: Full Body Stray Sheep bar jukebox, shown in the game’s opening.
The other piece of music for Project Re Fantasy was fully played during a live stream for its initial announcement in December 2016.
Catherine: Full Body will launch on the PS4 and PS Vita in Japan on February 14, 2019. It will be released for the PS4 in 2019 in the West.
Project Re Fantasy: A Fool’s Journey Begins currently does not have a release window or platform announced. More information on the game will be given following the release of Studio Zero’s first title, Catherine: Full Body.