Arthur and Peter are a twin boy. They are Devil and Angel sent down to earth from birth. They grew up in a church and became good twin brother. Father Frederick was the one who found and raised them as beloved two sons. Arthur was an ignorant, rude, and quiet boy. While Peter is a cheerful, friendly, and sociable boy. They really like cookies. Arthur has the Dark power, while Peter has the Light power. Father Frederick never told them about their true self as Devil and Angel