Which key is true?

Which key is true? a song by のる on Beatsfy

祇響～時のまなざし～ by のる ,
SUSANOO - Remake Version by のる ,
Travelers by のる ,
海鳥たち by のる ,
花の祭 -people's joy- by のる ,
街角の猫 by のる ,
Naberius by のる ,
Which key is true? by のる ,
空を超える日 by のる ,
残照の郷、行列は行く by のる ,
昏き自由を唄うもの by のる ,