Unbeknowest to humans, angels walk among us. Save for the occasional annual angelic convention, they are scattered across the globe interacting with humans and their crises. Chihaya and Kagetsuya consistently find themselves in different parts of the world dealing with an array of characters and their hopeless problems. This seems to be the only source of their worries until news arrives of a growing legion of fallen angels plagued by the "Black Cancer." What will happen when Chihaya and Kagetsuya are asked to find one of the feared Great Fallen Angels, Lord Seraphim? What is it about Chihaya that lands the Great Fallen Angel right at his doorstep?