It is not clear what language is used for Kōenji Hyakkei lyrics. For the most part, lyrics are reminiscent of Christian Vander's Kobaïan language (a notable exception is the song "Zoltan" from their 1994 self-titled album Hundred Sights of Koenji, a Kyrie).
The lyrics' language is unclear, but they resemble Christian Vander's Kobaïan language (a notable exception is the song "Zoltan" from their 1994 album Hundred Sights of Koenji).