Signa

You play as the main character, Signa, a Demon Gazer, one who possess the Demon Gaze, an Evil Eye that can capture demons. You defeat the demons, capture their souls, turn their souls into keys, and use them to your advantage.

Story
Signa is the childhood friend of Muse and Prim. The body modifications that was performed on him caused him to gains the power to control Demons with his Demon Gaze, but because of the modification to his body he has amnesia.