Fentanil is a depressive black metal band that was initially formed by two members, C22H28N2O - All Instruments and Lyrics, and Phoneutria - Vocals and Lyrics. After recording the first demo, vocalist Phoneutria left the band. Giving space to the new singer, Yakoushi. This formation was maintained for the next four releases, C22H28N2O was responsible for recording all instruments and lyrics and Yakoushi was responsible for the voices and lyrics. After the last split with the band Sadroom the band recruits two new members