Masatora Akutsu is a demon working undercover at a human high school, sent to scout recruits who can help Hell push back against the angels of Heaven. His new seatmate, transfer student Lily Amane, looks like an ideal catch until he discovers she is an angel herself. He falls for her anyway. The two go on sitting side by side, each keeping up a cover story and each refusing to concede anything to the other side of the war.