The Temple Demon, like most demons, was cruel and ruthless to humans. He appeared to be very defensive of his territory as he was irate. The demon also displayed a sense of superiority over Tanjiro when the two fought, boasting his quick recovery after getting hit in the chin. He shows up in 1 chapter, so this role would be able to audition for future characters.

I don't have a set voice for him, just make him a bit raspy with a medium-pitched voice.