.
So, if you find this analysis as reasonable interpretation, and think it explains the lyrical relation, for you, it has actually become the real meaning of the lyrics in relation to Tokyo Ghoul on the contingency an official statement from the band explaining the lyrics' relation to Tokyo Ghoul is not released.
The monster that you see Is it a part of me? It can also be referenced to Hinami and Touka's questioning of their lives as ghouls when they faced Mado, but everyone supported them to get through it.
Now when Ken wears the mask for a while this represents him accepting his Ghoul side like he did in episode 12 of the first season.
Still, if you listen to it more, I bet you'll like the melody too.
I'm not the biggest Tokyo Ghoul fan only on ep 6 or 7 of first season; Kaneki as a character is annoying me atm, but I'll finish it , but I can honestly say, the sound and music team have a good grasp of the atmosphere of the story and imo, are capturing it pretty well with the music.