The series follows Yōki, a man killed in a traffic accident who finds himself reincarnated as a demon in another world. Not wanting to become a Demon Lord, he works as a subordinate at the Demon Lord's castle. One day, a Hero's party invades the castle and attacks. However, he finds the party's priestess, Cecilia, cute and falls in love with her. He confesses his feelings to her, starting an unusual relationship between the two.
