I'm sorry who's carl again

Carl is illya’s older brother who lost himself after loosing to the girl w black hair. Illya is the girl with white long hair that accompanies the ml.

Ahh i guess he succumb to demon's power after losing ooohhh thanks!

ohh no no, after loosing he fell into a deep depression. He lost his motivation and then just disappeared one day. Ngl, i think we’ll see him back in the storyline as someone who's succumb to demon powers though, but that is only my guess.(￣∇￣")